Tweak Math.log on ia32/x64

ia32 and x64 more consistent now
1. use non-transcendental cache version of log for x64
2. use negative infinity constant instead of pushing to stack and loading to XMM register
3. remove movdbl, use movsd directly. movdbl seems confusing

BUG=
R=jkummerow@chromium.org

Review URL: https://codereview.chromium.org/27197013

Patch from Weiliang Lin <weiliang.lin2@gmail.com>.

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@17268 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
HeapProfiler: for the test purposes we would like to trace object movements.

When we have an untracked allocations we need to fix it.
It is a bit tricky process due to lack of logging.

I added FLAG_heap_profiler_trace_objects that enables log for object movements.

Drive by fix: with help of logging I found a bug in LeftTrim method for FixedArray.

BUG=none
R=svenpanne@chromium.org, yurys@chromium.org

Committed: https://code.google.com/p/v8/source/detail?r=17258

Committed: https://code.google.com/p/v8/source/detail?r=17263

Review URL: https://codereview.chromium.org/27694004

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@17269 ce2b1a6d-e550-0410-aec6-3dcde31c8c00