Elision of checks optimization.

Fix for Change-Id: Ide3ea09c0e60647da30226d43ae869ca612856f3
We now sharpen types in the verifier based on instance-of followed by ifeq/ifneq pattern.
Changed comments to conform to 100 char per line limit.
Added asserts.

	modified:   src/dex_file_verifier.cc
	modified:   src/verifier/method_verifier.cc
	modified:   src/verifier/register_line.cc

Change-Id: Ibc8804d78e9ea7caefc21034897a5a500ea014f0