This removes support for iterator loops (i.e. for-of loop constructs)
from the {FullCodeGenerator}. Consequently optimized code containing
such constructs must use the {BytecodeGraphBuilder} and can no longer
use the {AstGraphBuilder} for graph building.

R=bmeurer@chromium.org
BUG=v8:5657

Review-Url: https://codereview.chromium.org/2534883004
Cr-Commit-Position: refs/heads/master@{#41357}