This patch refactors the scanner bookmark in SkipLazyFunctionBody,
so that it is only used locally, instead of being passed to several
other methods.  It is replaced by a "may_abort" parameter and an
appropriate result denoting whether lazy parsing has been aborted.

It also applies the hack of aborting lazy parsing for arrow
functions that are considered to be "initialization functions".

R=adamk@chromium.org, vogelheim@chromium.org
BUG=
LOG=N

Review-Url: https://codereview.chromium.org/2297733002
Cr-Commit-Position: refs/heads/master@{#39072}