Ignore definitions that do not have SSA index in FlowGraphAllocator::CollectRepresentations.
Ignore definitions that do not have SSA index in FlowGraphAllocator::CollectRepresentations.

SSA building does not assign an index to definitions without uses and the rest of the allocator can cope with this treating output produced by such an instruction as temporary value.

R=srdjan@google.com
BUG=dart:8655

Review URL: https://codereview.chromium.org//12315017

git-svn-id: c93d8a2297af3b929165606efe145742a534bc71@18793 260f80e4-7a28-3924-810f-c04153c831b5

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