This fixes canonicalization of {SharedFunctionInfo} objects in the
{Compiler::GetSharedFunctionInfo} method when bytecode is preserved.
Eager compilation is only triggered when no code is present.

R=rmcilroy@chromium.org
TEST=mjsunit/regress/regress-crbug-638551
BUG=chromium:638551

Review-Url: https://codereview.chromium.org/2245263006
Cr-Commit-Position: refs/heads/master@{#38709}