Simplify HUnaryMathOperation::Canonicalize.

Made the logic architecture-independent, although we should really have some kind of instruction selection instead of trying to handle some weird cases at the hydrogen level.

Some tiny related cleanups on the way.

R=bmeurer@chromium.org

Review URL: https://codereview.chromium.org/141653015

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@18824 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
Delete v8_shell target now that chrome uses d8

BUG=331585
LOG=y
R=machenbach@chromium.org

Review URL: https://codereview.chromium.org/146763002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@18829 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
Mark weak fields of JSArrayBuffer and JSArrayBufferView as weak in heap snapshot.

BUG=337144
LOG=N
R=ulan@chromium.org, yurys@chromium.org

Review URL: https://codereview.chromium.org/138443009

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@18830 ce2b1a6d-e550-0410-aec6-3dcde31c8c00