Insert type guards for loads from arrays in nested loops.
Insert type guards for loads from arrays in nested loops.

To limit code size implications, only do it in methods that already
have type guards.

R=floitsch@google.com
BUG=
TEST=

Review URL: https://chromiumcodereview.appspot.com//10735026

git-svn-id: c93d8a2297af3b929165606efe145742a534bc71@9466 260f80e4-7a28-3924-810f-c04153c831b5

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