This fixes the existing workaround in {BytecodeGraphBuilder} where the
number of elements in an array literal is unknown just from the bytecode
alone and needs to be deduced from the constant elements.

Note that this is just a quick fix to prevent calling the fast-clone
stub for boilerplates that are too big to fit on a regular page. In the
long run we need something more solid here.

R=mvstanton@chromium.org
TEST=mjsunit/regress/regress-crbug-669850
BUG=chromium:669850

Review-Url: https://codereview.chromium.org/2542633002
Cr-Commit-Position: refs/heads/master@{#41420}