Improve Promise coverage: Promise.prototype.then

Destructuring Binding - syntax and simple initialization

Add tests for instanceof operator when prototype property is primitive or getter

Object.{values,entries} tests

Add tests that assert sequential job execution

Update test metadata to accurately describe the more complete set of
assertions.

Because these tests concern the behavior of the PromiseReactionJob
abstract operation itself, they should avoid assumptions about the
correct implementation of that operation. Specifically: they should not
rely on the behavior of abupt completions returned from "reaction
handler" functions.

Re-implement tests to express control flow expectations using the
`$DONE` function only.

By organizing files according to the structure of the specification,
test coverage can be more methodically evaluated.

Use names that describe the behavior (not the location in the
specification) as per the current convention.

These tests concern the behavior of PerformPromiseThen for settled
Promises. That abstract operation behaves differently for pending
promises, so the file naming scheme should reflect this distinction in
order to support the future implementation of additional tests.

Add a test verifying that |let<newline>let| isn't subjected to ASI, matches LexicalDeclaration, and is then treated as an early error

Add tests verifying that ASI can't occur after the leading let/const in |let let|, |let let = "...";|, and |const let = "...";|.  Each matches the LexicalDeclaration production, then triggers an early error before evaluation because it attempts to bind "let".

Add test cases for recent ES2016 fixes

- lastIndex in RegExp.prototype[Symbol.split]: tc39/ecma262@08b4756747f9c967058239df627da544412740a6
- Missing number conversion in DataView.prototype.setXXX: tc39/ecma262@4f875fe96dcbd5e6363dd3d5b510cd5109199f5b
- Negative zero byteoffset in TypedArray: tc39/ecma262@2d1ed20db778e8f69f66ba76b351b9322fd38495
- EvalDeclarationInstantiation throws TypeError: tc39/ecma262@2be6968715946a4763f6ca8633e311ab7ce63577
- BindingRestElement allows BindingPattern: tc39/ecma262@d322357e6be95bc4bd3e03f5944a736aac55fa50
- Eval in parameters with computed property keys: tc39/ecma262@04e2e9b7197a33612202e85065e3f8d8385fbcef
- Use strict with non-simple parameters: tc39/ecma262@15b0db41edd0e519e94668bf13765fe458840766
- __proto__ in strict mode: tc39/ecma262@5c1984334d6d42538527bd022e68bfbfee5cb652

Per https://github.com/tc39/proposal-object-values-entries/commit/9bd195495030e4a40b7b558dc857ce57549b056d and https://github.com/tc39/test262/pull/453#discussion_r47556411

Add tests for ArrayBuffer and ArrayBuffer.prototype.slice

Improve test coverage for various Promise methods

Remove unnecessary ES2015 syntax; add feature flags where appropriate.

This allows these tests to be more easily reused to test Promise
implementations in isolation.

Updates for ES2016 Draft 2015-12-01

Test built-in function requirements of Promise and Proxy helper functions

- RegExp.prototype[Symbol.split] calls ToUint32 (https://github.com/tc39/ecma262/issues/92)
- Species lookup removed from Promise.all and Promise.race (https://github.com/tc39/ecma262/issues/151)
- Generator functions are no longer constructors (https://github.com/tc39/ecma262/pull/171)

Fixes #444

Revert primitive wrapper prototypes and String#split to ES5

- if-statement completion value semantics was not properly updated in ES2015

- Don't interpret date-only as local time