This introduces a JSBitwiseNot operator and lowers it either to a
speculative xor with -1 (when we have Number feedback) or to
a stub call. The stub is also new.

Bug: v8:6791
Change-Id: I362e52de8a741dc5db044c406543878e407eb2ed
Reviewed-on: https://chromium-review.googlesource.com/778839
Commit-Queue: Georg Neis <neis@chromium.org>
Reviewed-by: Jaroslav Sevcik <jarin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#49539}