Revert of Introduce KeepAliveWhilePending to ScriptPromiseResolverWithContext. (https://codereview.chromium.org/311733004/)

Reason for revert:
This CL breaks the build.

Original issue's description:
> Introduce KeepAliveWhilePending to ScriptPromiseResolverWithContext.
> 
> Some modules, for example WebMIDI and WebCrypto, needs "Async Initializer".
> The initializer should stay alive until the initialization succeeds (i.e. the
> associated Promise is resolved), the initialization fails
> (i.e. rejected), or the associated ExecutionContext is stopped.
> This CL introduces the the constructor mode ScriptPromiseResolverWithContext.
> If KeepAliveWhilePending is specified, the created resolver stays alive while
> one of the above conditions meets.
> Each initializer can stay alive by inheriting ScriptPromiseResolverWithContext.
> 
> This CL rewrites WebMIDI and WebCrypto async operations with it.
> 
> BUG=361041
> 
> Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=176381
TBR=yhirano, haraken, eroman, toyoshim@chromium.org
NOTREECHECKS=true
NOTRY=true

Review URL: https://codereview.chromium.org/339443004

git-svn-id: svn://svn.chromium.org/blink/trunk@176383 bbb929c8-8fbe-4397-9dbb-9b2b20218538