Some JavaScript source files are only relevant in the context of the
Test262 website. They should not be explicitly included by individual
tests, so their presence in the `harness/` directory alongside "include"
files is misleading.

Move the scripts to a location within the `website/` directory to
better-reflect their intended use. Update the relevant HTML templates
with the new locations.

Although test files once expressed dependencies on external files using
a global `$INCLUDE` function, that pattern was removed in favor of
declarative meta-data [1].

Remove the associated logic from the Python runner and the browser.

[1] See commit d4354d14.

The `fnExists` function defines a generic way to determine if any number
of values are function instances. Because it is only used by a single
test, the additional complexity required by the generalized code (and
the organizational drawbacks to maintaining another "include" file) are
not justified. Remove the file and update the test to assert the
function's existence directly.

The `environment.js` file has been empty since its initial introduction
to this project [1]. It has no effect on any of the contexts in which it
is currently referenced, so it may be safely removed.

[1] be82787a

It was missing vars which was causing issues with our test harness
since we run all the files in strict mode.

Unlike the console runner, the browser runner does not modify the
strictness of tests prior to running them. Regardless of a given test's
metadata, it runs every test exactly once, and it never enables strict
mode. This means that tests intended to function in strict mode must
declare the "use strict"; directive prologue in addition to the
`onlyStrict` flag.

For any test that specifies the `onlyStrict` metadata flag, transform
the source code by injecting a "use strict" directive prologue prior to
running the test.

Since the Python runner was updated to include `assert.js` in all tests
unconditionally, a number of tests have been written that implicitly
rely on its presence. The browser runner does not currently provide this
file's contents to these tests, so they fail unconditionally.

Update the browser runner to inject that file's contents into every test
context.

Note: the existing approach to file retrieval (namely loading via
synchronous XHR requests) is inefficient and deprecated in some
browsers. It is honored here for the sake of consistency and to minimize
the changeset necessary to fix the browser runner.

The `$PRINT` helper function has no effect on test behavior. The
following tests use it to report assertion outcomes (and as a result
will fail silently):

- test/language/function-code/S10.2.1_A4_T2.js
- test/language/function-code/S10.2.1_A5.1_T1.js
- test/language/function-code/S10.2.1_A5.1_T2.js
- test/language/function-code/S10.2.1_A5.2_T1.js

Remove the function definition and all references within tests. Update
tests that use it as an error reporting mechanism to instead use an
appropriate `assert` helper function.

This function is equivalent to `$ERROR` (which is automatically included
in test environments). Remove the harness file that defines the
function, remove references to the file from test `includes` lists, and
update scripts to instead invoke the `$ERROR` function.

- Remove no longer needed noStrict flags.
- Change tests to use propertyHelper.js for strict mode compatibility.
- Add tests for return value of `delete` operator, e.g. `delete Array.prototype === false`.
- Add non-writable tests for global NaN property.
- Split some tests to run in strict mode.
- Change tests with global `var length` declaration to use a different variable name for browser environments.
- Merge duplicated tests symbol-data-property-configurable-non-strict and symbol-data-property-configurable-strict.
- Merge duplicated tests symbol-data-property-writable-non-strict and symbol-data-property-writable-strict.
- (And a small change in propertyHelper to reduce code duplication in function call.)

The `testBuiltInObject` function verifies the presence of the specified
properties for *all* object types (not just function objects). Update
the error messages to reflect this.

Only attempt to re-set the property value in cases where it was
successfully modified as part of the function's execution. This avoids
errors when the underlying value is not writable. Rename the internal
result-tracking variable to make this more clear.

When invoked without a custom assertion message, `assert.sameValue` and
`assert.notSameValue` automatically create a message that describes the
actual and expected values.

Extend both assertion methods to also include this information in cases
where a custom message has been specified.

These tests are derived from the following files within the Google V8 project:

    	test/mjsunit/harmony/array-fill.js
    	test/mjsunit/harmony/array-find.js
    	test/mjsunit/harmony/array-findindex.js
    	test/mjsunit/harmony/array-from.js
    	test/mjsunit/harmony/array-of.js

In ES6 the function length property was changed to become
configurable.

After checking the writability of a given property, restore the property
value to its original state.

First check if descriptor is set up correctly, then actually
verify that the attribute (writability, enumerability,
configurability) is as expected.

- this change hits all files that use
dataPropertyAttributesAreCorrect or
acccessorPropertyAttributesAreCorrect

Major changes:
- remove include of runTestCase.js,
dataPropertyAttributesAreCorrect.js and
acccessorPropertyAttributesAreCorrect.js
- add include of propertyHelper.js
- remove function testCase() and call to
function runTestCase()
- instead of collecting test state into booleans,
which are eventually returned from runTestCase,
test conditions and throw errors immediately
- use negative: to check error types instead of
using `instanceof` in a catch() block

Selected commit logs follow:

manual conversion of accessorPropertyAttributesAreCorrect() test
 - remove runTestCase
 - remove wrapping testCase function
 - unindent
 - remove includes of runTestCase & accessor...
 - add include of propertyHelper.js
 - unpack final two args 'true, false' to explicit inline
   tests of isEnumerable and isConfigurable
 - unpack setter test into inline logic
 - unpack getter test into inline logic

used script to replace includes: frontmatter
with propertyHelper.js ; manually added back
references to fnGlobalObject() where needed

additional helper functions

add helper functions for get and writable
duplicate runTestCase so can remove runTestCase.js from
includes of all tests in batch

use keyboard macros to simplify repetitive conversions
remove auto-save file accidentaly committed

minor changes, manually remove runTestCase from remaining files
lint etc. fixes

remove now-obsolete harness files

make strict/nonstrict variants

tests where behavior is different in strict/nonstrict
need two variants

- strict mode throws on assign to read-only element (no setter fn)
- strict mode separates named arguments from arguments[]

fix indentation

cleanup minor issues

reviewing 15.2.3.7-9 tests, found some minor issues

- indentation/spacing
- duplicate test (eg, direct test of value and dataProp...)
- remove needless try/finally
- use assert.. helpers in place of if(is..
- rename some assertions to 'e'

rename assertX to verifyX
new helper fn sameValue
test "set" as well as get
reverse order of checks
restore test of desc2
restore test of length
restore test of ownProperty
incorporate suggestions re order of ops, Object.prototype
add test of sameValue helper
restore return value in getter
restore second defineProperty call
restore check of explicit "false"
restore explicit test of TypeError
set noStrict flag on arguments changes
rename catch var to "e"	b4ad0e6
remove dataPropertyAttributesAreCorrect from tests	0d83ff2
remove accessorPropertyAttributesAreCorrect from tests	bb926f3
remove {data,accessor}Property... fns from harness

fix writable check on array.length

call $ERROR if expected exception not thrown
fix Epected => Expected typo

use assert._isSamevalue