Allow monomorphic loads when static type is known.

This allows Crankshaft to generate monomorphic loads when the receiver
type is statically known even though the load site has polymorphic type
feedback. This applies to inlined constructor calls and literals.

R=jkummerow@chromium.org
TEST=mjsunit/compiler/property-static

Review URL: https://codereview.chromium.org/12051058

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@13500 ce2b1a6d-e550-0410-aec6-3dcde31c8c00