Port r11278 (e5dc7ebd).

Original commit message:

Skip canonicalization check in LStoreKeyedFastDoubleElement when it is not needed:

- if value is a result of integer32 to double conversion (can't be NaN);

- if value was loaded from fast double backing store (already canonicalized).

BUG=
TEST=

Review URL: https://chromiumcodereview.appspot.com/10071004
Patch from Daniel Kalmar <kalmard@homejinni.com>.

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@11366 ce2b1a6d-e550-0410-aec6-3dcde31c8c00