Improve code for shifts and bitwise operations.

Improve code for shifts and bitwise operations.

- JavaScript shifts can be used for operands in certain ranges.

- Coercion from signed-32 to unsigned-32 can be omitted if
  - it is a no-op
  - the context performs the coercion
  - the context is insensitive to the most significant bit

R=jmesserly@google.com

Committed: https://github.com/dart-lang/dev_compiler/commit/ec95b3c45819f4d0de847588fdaa752a8e4651fb

[sra1, 2016-04-29 00:37:29]

Patchset #1 (id:1) has been deleted

[sra1, 2016-04-29 00:37:37]

Patchset #1 (id:20001) has been deleted

[sra1, 2016-04-29 00:40:56]

Patchset #1 (id:40001) has been deleted

[sra1, 2016-04-29 00:44:11]

sra@google.com changed reviewers:
+ jmesserly@google.com

[Jennifer Messerly, 2016-04-29 17:06:17]

jmesserly@google.com changed reviewers:
+ vsm@google.com

[Jennifer Messerly, 2016-04-29 17:06:17]

I don't know if someone who knows these bitops better wants to take a look
(vsm?) but LGTM :)

[sra1, 2016-04-29 19:22:26]

Description was changed from

==========
Improve code for shifts and bitwise operations.

- JavaScript shifts can be used for operands in certain ranges.

- Coercion from signed-32 to unsigned-32 can be omitted if
  - it is a no-op
  - the context performs the coercion
  - the context is insensitive to the most significant bit
==========

to

==========
Improve code for shifts and bitwise operations.

- JavaScript shifts can be used for operands in certain ranges.

- Coercion from signed-32 to unsigned-32 can be omitted if
  - it is a no-op
  - the context performs the coercion
  - the context is insensitive to the most significant bit

R=jmesserly@google.com

Committed:
https://github.com/dart-lang/dev_compiler/commit/ec95b3c45819f4d0de847588fdaa...
==========

[sra1, 2016-04-29 19:22:28]

Committed patchset #1 (id:50001) manually as
ec95b3c45819f4d0de847588fdaa752a8e4651fb (presubmit successful).