[turbofan] Remove indirection in JSToBoolean/JSUnaryNot lowering.

[turbofan] Remove indirection in JSToBoolean/JSUnaryNot lowering.

This reduces the overhead of typed lowering, because we lower
JSToBoolean/JSUnaryNot directly if possible, instead of first lowering
to AnyToBoolean, and then letting the SimplifiedOperatorReducer do the
further lowering.

Also remove some obsolete tests from the cctest suite that have since
been removed by proper unittests. And improve unitttest coverage for the
typed lowering cases.

R=mstarzinger@chromium.org

Committed: https://crrev.com/a75e4cea8f454c6cdb71025903812689894cd8aa
Cr-Commit-Position: refs/heads/master@{#27295}

[Benedikt Meurer, 2015-03-19 09:42:36]

PTAL

[Michael Starzinger, 2015-03-19 10:10:54]

LGTM, I like it!

https://codereview.chromium.org/999173003/diff/1/src/compiler/js-typed-loweri...
File src/compiler/js-typed-lowering.cc (right):

https://codereview.chromium.org/999173003/diff/1/src/compiler/js-typed-loweri...
src/compiler/js-typed-lowering.cc:543: // JSUnaryNot(x:string) =>
NumberEqual(x.length,#0)
nit: Can we add a one-liner comment that this is safe for the load to be
effect-free (i.e. not linked into effect chain) because we assume String::length
to be immutable?

https://codereview.chromium.org/999173003/diff/1/src/compiler/js-typed-loweri...
src/compiler/js-typed-lowering.cc:572: // JSToBoolean(x:string) =>
NumberLessThan(#0,x.length)
nit: Likewise about the comment.

[Benedikt Meurer, 2015-03-19 10:13:20]

Committed patchset #2 (id:20001) manually as
a75e4cea8f454c6cdb71025903812689894cd8aa (presubmit successful).

[commit-bot: I haz the power, 2015-03-19 10:13:22]

Patchset 2 (id:??) landed as
https://crrev.com/a75e4cea8f454c6cdb71025903812689894cd8aa
Cr-Commit-Position: refs/heads/master@{#27295}