Add more type annotations to patchFactory() in src/core.js
Add more type annotations to patchFactory() in src/core.js

This makes Closure Compiler type check the function better.

Note that these annotations won't be necessary once we switch to Closure
Compiler's new type inference. Currently, the new type inference is not
enabled due to false positives / extra warnings. I will make the switch
once NTI is more stable.

PolymerLabs/incremental-dom,jridgewell/incremental-dom,jridgewell/incremental-dom,sparhami/incremental-dom,sparhami/incremental-dom,google/incremental-dom,google/incremental-dom,sparhami/incremental-dom,google/incremental-dom,PolymerLabs/incremental-dom,jridgewell/incremental-dom,PolymerLabs/incremental-dom,sparhami/incremental-dom