Avoid creating unnecessary environments during SSA renaming.
Avoid creating unnecessary environments during SSA renaming.

Only instructions that can deoptimize and Goto-instructions
ever need an environment.
Review URL: https://codereview.chromium.org//11225028

git-svn-id: c93d8a2297af3b929165606efe145742a534bc71@13871 260f80e4-7a28-3924-810f-c04153c831b5

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