ARM64: Reland faster immediate check

ARM64: Reland faster immediate check

Improve the code used to check for encodable logical immediates, fix some corner
cases associated with moving kWMinInt into W registers, and add tests.

BUG=
R=ulan@chromium.org

Committed: https://code.google.com/p/v8/source/detail?r=22148

[m.m.capewell, 2014-07-01 16:56:25]

Try server reports success, so this shouldn't cause problems this time.

[ulan, 2014-07-02 06:42:51]

lgtm

[m.m.capewell, 2014-07-02 09:52:38]

Committed patchset #1 manually as r22148 (presubmit successful).