Fix stack height assertion code and free up a bit in the Function tag bits.

Fix stack height assertion code and free up a bit in the Function tag bits.

The bit has_finally was only used to skip the checking of the stack height
at return statements: There was an unused value floating on top of the
expression stack in unoptimized code if the finally block preceded a normal
return statement. Normallyi, that does not cause harm. Optimized code is not
affected since it has a fixed stack size for expression evaluation.

This CL fixes the stack height for functions with try-finally by introducing
a temporary local where the return value is saved before an inlined
finally-block.

R=srdjan@google.com

Committed: https://code.google.com/p/dart/source/detail?r=32157

[srdjan, 2014-01-29 19:01:55]

lgtm

[Florian Schneider, 2014-01-30 12:12:42]

Committed patchset #1 manually as r32157 (presubmit successful).