dart2js: simplify ssa-generate constant.

dart2js: simplify ssa-generate constant.

The registry was already doing the work that was in generateConstant.

R=sigurdm@google.com

Committed: https://code.google.com/p/dart/source/detail?r=41715

Reverted: https://code.google.com/p/dart/source/detail?r=41720

[floitsch, 2014-11-13 14:39:15]

floitsch@google.com changed reviewers:
+ sigurdm@google.com

[sigurdm, 2014-11-13 14:40:01]

LGTM

[floitsch, 2014-11-13 14:40:19]

Committed patchset #1 (id:1) manually as 41715 (presubmit successful).

[floitsch, 2014-11-13 16:47:47]

floitsch@google.com changed reviewers:
+ johnniwinther@google.com
- sigurdm@google.com

[floitsch, 2014-11-13 16:47:48]

Had to revert because of unused functions:
==
Hint: The method 'registerTypeConstant' is never called.
Consider deleting it.
==

That's true, and I could just delete it, but it looks to me like
`registry.registerCompileTimeConstants` doesn't do the same thing.

[Johnni Winther, 2014-11-14 08:33:32]

https://codereview.chromium.org/721093003/diff/1/pkg/compiler/lib/src/ssa/cod...
File pkg/compiler/lib/src/ssa/codegen.dart (left):

https://codereview.chromium.org/721093003/diff/1/pkg/compiler/lib/src/ssa/cod...
pkg/compiler/lib/src/ssa/codegen.dart:1821: if (constant.isType) {
We need to move this to JavaScriptBackend.registerCompileTimeConstantInternal
under a flag that the constant occurred in executed code (i.e. not in metadata).
It is needed to detect registration of custom elements.