fix nested type-arg-list parsing.

Just like old C++, Foo<Bar<Baz>> has been failing to compile due to ">>"
operator.

Luckily, ">>" is valid only in "=" ~~~ ";" (const expression) in AIDL.
Introduced "CONST_MODE" as a starting condition for ">>" & "<<" so that
when we're parsing type-arg-list, ">>" & "<<" tokens are not considered.

Bug: n/a
Test: aidl_unittests & aidl_integration_test
Change-Id: I969a4ca7a16f6fcd49348d766792c6b40b004c01
2 files changed