Make AST generation deterministic: always call a static getter if it exists, regardless if the stat…

Make AST generation deterministic: always call a static getter if it exists, regardless if the statuic field was initialized or not. Previously we may have created a LoadStaticFieldNode dependgin if the static field was already intialized at compile time.
Note that we do not generate implicit static getter nodes if their initialization is trivial.

R=hausner@google.com

Committed: https://code.google.com/p/dart/source/detail?r=23825

[hausner, 2013-06-10 18:44:55]

lgtm

[srdjan, 2013-06-10 19:32:07]

Committed patchset #3 manually as r23825 (presubmit successful).