Cache the current token in some functions in the parser
Cache the current token in some functions in the parser

Avoid some calls to CurrentToken(). Compiling all of dart2js, this saves
about 10% of calls to CurrentToken(). There is no measurable performance
difference (using wall-clock time).

R=iposva@google.com, srdjan@google.com

Review URL: https://codereview.chromium.org//305653002

git-svn-id: c93d8a2297af3b929165606efe145742a534bc71@36763 260f80e4-7a28-3924-810f-c04153c831b5

dartino/dart-sdk,dart-archive/dart-sdk,dartino/dart-sdk,dart-lang/sdk,dart-lang/sdk,dart-archive/dart-sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dartino/dart-sdk,dartino/dart-sdk,dart-lang/sdk,dart-archive/dart-sdk,dart-archive/dart-sdk,dart-archive/dart-sdk,dartino/dart-sdk,dart-lang/sdk,dart-archive/dart-sdk,dart-archive/dart-sdk,dart-archive/dart-sdk,dart-lang/sdk,dart-archive/dart-sdk,dartino/dart-sdk,dartino/dart-sdk,dartino/dart-sdk,dartino/dart-sdk