ParseArrowFunctionLiteral was erroneously checking AllowsLazyCompilation
rather than AllowsLazyParsing when deciding whether to parse lazily.
This meant that lexically-scoped variables that had no other referents
wouldn't get closed over properly.
BUG=chromium:580934, v8:4255
LOG=y
Review URL: https://codereview.chromium.org/1630823006
Cr-Commit-Position: refs/heads/master@{#33530}
