Fix ARM64 build

The android toolchain for L now has a proper version (21)

BUG=none
TBR=rossberg@chromium.org
LOG=n

Review URL: https://codereview.chromium.org/777273004

Cr-Commit-Position: refs/heads/master@{#25711}
Do not reflect uninitialized 'let' and 'const' in scope mirrors.

R=yangguo@chromium.org,aandrey@chromium.org
BUG=v8:3743
LOG=N

Review URL: https://codereview.chromium.org/758603004

Cr-Commit-Position: refs/heads/master@{#25712}
update test case for "Disable neutering on embedded arraybuffers"

  This test case ( added by git: 4c7effe56e8dbe8e2df51bab967c8e1d251f3a66 ).
  should has different implementation for Turbofan and crankshaft.

BUG=

Review URL: https://codereview.chromium.org/774163005

Cr-Commit-Position: refs/heads/master@{#25713}
Better message location for 'super(...)' restriction error.

R=arv@chromium.org
BUG=v8:3330
LOG=N

Review URL: https://codereview.chromium.org/776563002

Cr-Commit-Position: refs/heads/master@{#25714}
Optimize add/set/delete operations for string keys in Maps and Sets

This was previously landed in commit 8599f5f, but failed the
collections mjsunit test on ia32 with --deopt-every-n=1. The fixed
patch adds a ClearFlag(HValue::kCanOverflow) call after every
arithmetic operation, which should remove all the deopt points in these
intrinsics.

Ideally, it seems like there should be a way to verify that there are
no deopt points for these inline optimized functions, since there's
nothing to deopt to. But I don't currently know of such a thing.

Review URL: https://codereview.chromium.org/782073002

Cr-Commit-Position: refs/heads/master@{#25715}
Ignore tests that fail on nosnap apparently for infa reasons.

TBR=arv@chromium.org
BUG=v8:3744
LOG=N
NOTRY=true

Review URL: https://codereview.chromium.org/746743003

Cr-Commit-Position: refs/heads/master@{#25716}