Bug 666399 - New Harmony syntax for generators. r=Waldo

Add a GeneratorKind enumeration, and use it in the parser and runtime to
indicate whether a function is a non-generator, a legacy generator, or a
star generator.

Always parse "yield" as TOK_YIELD, regardless of the version.  Add
TokenStream::currentName() to retrieve the current token's name, which
works for TOK_NAME or TOK_YIELD.  The parser should check the validity
of "yield" as a name, if needed, using checkYieldNameValidity().

Parse "function*" as the StarGenerator GeneratorKind, and allow star
generators to be lazily parsed.

Separate parsing of return statements from yield expressions.
Bug 878144 - Remove nsExternalHelperAppService::FixFilePermissions. r=paolo
Bug 899861 - Animated gifs should not wait to play until fully downloaded. This is a partial backout of 717872 with the intent to re-enable using the separate FrameAnimator class. Hide the new approach behind #define USE_FRAME_ANIMATOR for now. r=bgirard
Bug 905058 - Before accessing the UIA root element make sure the global com ptr is populated. r=bbondy
Bug 887054 - Part 1: Refactor xpcshell test harness to support parallel test runs, disabled in automation. r=ahal, r=ted
Bug 887054 - Part 2: Add parallel warning and support for --sequential to mach xpcshell-test. r=gps
Bug 887054 - Part 3: Synchronize blocks of output when running xpcshell tests in parallel. r=ted
Bug 887054 - Part 4: Mark dom/network/tests/unit/test_tcpserversocket.js to run sequentially. r=ahal