Improve type test and type equality for generics (issue 15148).

Improve type test and type equality for generics (issue 15148).

R=srdjan@google.com

Committed: https://code.google.com/p/dart/source/detail?r=30546

[regis, 2013-11-21 18:41:53]

Currently, the full flattened vector of a generic type is considered in a type
test or type equality test.

This change makes these tests more efficient by only considering the portion of
the type vector reflecting the type parameters of the type class, and ignoring
the portion reflecting the type arguments of the superclasses, since they are
fully defined in terms of the type parameters.

This causes a regression for a brittle test involving a recursive type. This
will be addressed when fixing issue 15244.

[srdjan, 2013-11-21 20:48:43]

lgtm

[regis, 2013-11-21 21:31:02]

Committed patchset #2 manually as r30546 (presubmit successful).