This reverts commit a01de4a7.

The tests are explicitly for bad hex chars at certain indexes, and that
rogue `%` was giving false positives.

* Move decimalToHexString into harness instead of duplicating it in multiple files

* Optimize decimalToHexString and support numbers greater than 65535

* Replace alternative decimalToHexString function with include for decimalToHexString.js

* Add decimalToHex2String to return the string representation of a two-digit hex-number

* Replace decimalToHex2String with decimalToPercentHexString to return the percent hex-encoded string of a two-digit hex-number

* Replace two String.fromCharCode calls with a single call

* Further reduce string concatentations in decodeURI[Component] tests

* Remove unnecessary Test262Error error handling in catch-clauses

* Remove try/catch wrappings in decodeURI/encodeURI tests

The harness file `Test262Error.js` has not contained executable code since it
was introduced in this project [1]. The definition of the `Test262Error`
function has consistently been located in the `sta.js` harness file which test
runners are expected to inject into the test environment.

Remove the file and all references to it.

[1] See commit c33bf0e0

Note: Already uses the updated DataView function lengths from tc39/ecma262#266 (ES2016 Draft 2015-12-20)

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.)

Add missing "var" declarations and noStrict flags.

Part of issue #35.