Use 16 instead of 4 for determining member offsets.

This avoids UBSan warnings about unaligned memory access.

BUG=

Review URL: https://codereview.chromium.org/734873002

Cr-Commit-Position: refs/heads/master@{#25396}
Re-land r25392 Use a stub in crankshaft for grow store arrays.

Code was vulnerable to different evaluation order in Clang.

R=danno@chromium.org

Review URL: https://codereview.chromium.org/726693004

Cr-Commit-Position: refs/heads/master@{#25397}
Prototype for a client-side performance trybot script.

BUG=chromium:374740
LOG=n
TEST=tools/try_perf.py sunspider octane
R=phajdan.jr@chromium.org

Review URL: https://codereview.chromium.org/734403002

Cr-Commit-Position: refs/heads/master@{#25398}
Fix loop information computation for floating loops.

R=jarin@chromium.org
TEST=cctest/test-scheduler/LoopedFloatingDiamond3

Review URL: https://codereview.chromium.org/726953002

Cr-Commit-Position: refs/heads/master@{#25399}
Fix disabling all break points from within the debug event callback.

BUG=chromium:432493
LOG=Y

Review URL: https://codereview.chromium.org/728103008

Cr-Commit-Position: refs/heads/master@{#25400}
Remove ambiguous getter for operator value counts.

R=titzer@chromium.org

Review URL: https://codereview.chromium.org/735583003

Cr-Commit-Position: refs/heads/master@{#25401}
v8::String::Concat must not throw.

R=dcarney@chromium.org
BUG=chromium:420240
LOG=Y
API=v8::String::Concat may return empty handle on overflow.

Review URL: https://codereview.chromium.org/735763002

Cr-Commit-Position: refs/heads/master@{#25402}