Support defining console variables with var consoleVar = someValue syntax
Support defining console variables with var consoleVar = someValue syntax

rename $var to $consoleVariables

move detection of JS console logic to .dart code from .js code
See https://codereview.chromium.org/24989007/ for the matching Blink change.

BUG=
R=blois@google.com, vsm@google.com

Review URL: https://codereview.chromium.org//25570002

git-svn-id: c93d8a2297af3b929165606efe145742a534bc71@28243 260f80e4-7a28-3924-810f-c04153c831b5

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