When generating code for ia32, make sure that there is enough reloc space

When generating code for ia32, make sure that there is enough reloc space

Compare with LCodeGen::FinishCode

BUG=none
R=jarin@chromium.org,mstarzinger@chromium.org
LOG=n

Review URL: https://codereview.chromium.org/777243002

Cr-Commit-Position: refs/heads/master@{#25679}