dart2js cps: Streamline expressions and primitives.

dart2js cps: Streamline expressions and primitives.

SetStatic, SetField, and SetMutableVariable are now primitives instead
of interior expressions. They are valueless primitives, i.e. they are
bound by LetPrim but their value is never referenced.

This should simplify basic block traversal, since there are now fewer
types of interior expressions.

The four remaining interior expressions are: LetPrim, LetCont,
LetHandler, and LetMutable. Incidentally, these are exactly the four
expressions that can bind definitions.

GetMutableVariable and SetMutableVariable have also been renamed
to GetMutable and SetMutable to be uniform with LetMutable.

BUG=
R=karlklose@google.com

Committed: https://github.com/dart-lang/sdk/commit/4d933a2d0d50d0b0ae6e55de6ad0bee6b1705154

[asgerf, 2015-07-20 13:35:22]

asgerf@google.com changed reviewers:
+ karlklose@google.com

[asgerf, 2015-07-20 13:35:23]

I put the class rename in a separate patch. Hopefully it's a bit easier to
review that way.

https://codereview.chromium.org/1240263002/diff/1/pkg/compiler/lib/src/tree_i...
File pkg/compiler/lib/src/tree_ir/tree_ir_builder.dart (left):

https://codereview.chromium.org/1240263002/diff/1/pkg/compiler/lib/src/tree_i...
pkg/compiler/lib/src/tree_ir/tree_ir_builder.dart:305: if (variable == null)
return visit(node.body);
This was dead code, left behind after another refactoring.

https://codereview.chromium.org/1240263002/diff/1/tests/compiler/dart2js/back...
File tests/compiler/dart2js/backend_dart/sexpr_unstringifier.dart (right):

https://codereview.chromium.org/1240263002/diff/1/tests/compiler/dart2js/back...
tests/compiler/dart2js/backend_dart/sexpr_unstringifier.dart:882: }
These cases we simply missing from the parser before. They are not really
related to the change.

[karlklose, 2015-07-20 13:41:08]

LGTM!

[asgerf, 2015-07-20 13:59:46]

Committed patchset #2 (id:20001) manually as
4d933a2d0d50d0b0ae6e55de6ad0bee6b1705154 (presubmit successful).