- 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
- Remove with-statements (minor change in behaviour - primitive vs wrapper lookup, but does not seem too important for these tests)

Part of issue #35.

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

    test/mjsunit/es6/typed-array-iterator.js
    test/mjsunit/es6/arguments-iterator.js
    test/mjsunit/es6/string-iterator.js
    test/mjsunit/es6/collection-iterator.js

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

	test/mjsunit/harmony/private.js

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

    test/mjsunit/es6/templates.js

Some of these tests include non-printable characters, causing git to
infer that they are binary files. Introduce a `.gitattributes` file to
configure git to consistently display the source text of all JavaScript
files.

Fixes #185
Fixes #186

v8 would fail this test, so it would be nice to have it