GetProperty CSA implementation bailouts prototype lookup when the
holder is a typed array, which is to handle integer indexed exotic
cases. However, this strict condition made too much overheads for
search of common names such as "constructor". This CL checks the
first character of a name, and do not bailout if we are sure that
the name cannot be a special index.

Bug: v8:4911, v8:7161
Change-Id: I2229ff3bebe14a452718e0b1f8354bb05437c09c
Reviewed-on: https://chromium-review.googlesource.com/842963Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Commit-Queue: Jakob Kummerow <jkummerow@chromium.org>
Cr-Commit-Position: refs/heads/master@{#50414}