Separate the array/string .length load from the bounds check.

This is done in preparation to inline more array and array view
operations.

Since the length is immutable for fixed length arrays, it allows
hoisting the load out of loops.
Review URL: https://codereview.chromium.org//12088108

git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge/dart@17984 260f80e4-7a28-3924-810f-c04153c831b5
5 files changed