MIPS64: Load prototype from map in PropertyHandlerCompiler::CheckPrototypes.

Port 100db75808486b9a85b5ba6384f27b3274438684

BUG=v8:3629
LOG=N

Review URL: https://codereview.chromium.org/755693002

Cr-Commit-Position: refs/heads/master@{#25497}
Reset code age on the cloned code when serializing.

R=mvstanton@chromium.org

Review URL: https://codereview.chromium.org/757983002

Cr-Commit-Position: refs/heads/master@{#25498}
Refactor use of Isolate::use_crankshaft.

R=jkummerow@chromium.org

Review URL: https://codereview.chromium.org/755883003

Cr-Commit-Position: refs/heads/master@{#25499}