V8 CPU profiler: source level support
Merge pull request #50 from dp7/master

V8 CPU profiler: source level support
Merge pull request #52 from fujunwei/rebase-simd-next

Rebase simd from M37 to M38
Change JS function names in simd128.js to JS prefix.
Change the name of conversion functions according to spec.
Implement SIMD.float32x4.select API.
Add the 1 argument constructor for SIMD types.