this includes various cleanups found along the way:
* various issues with JS annotations, see #30043
* getGenericClass is now optimized when used in a JS builtin with a Type literal
* typed list literals should be slightly faster to create
* memoized getters used by dart:_runtime should be faster
* registerExtension should be a tad faster, and now understands JSArray
* dart.bind "safeName" hack gone in codegenerator
* JSArray<E>.runtimeType returns List<E>
* JSArray<E>.noSuchMethod works
* cleans up code that generates `setExtensionBaseClass` (used only by JSArray)
* _throwUnsafe helper for generating a `throw` in --unsafe compile mode
* fix tearoff of JS interop types (_emitSimpleIdentifier)
* fix TODO about splitting LazyJSType and AnonymousJSType
* fix is/as/cast methods on TypeRep and related classes
* fix codegenerator to not tearoff "hashCode" and "runtimeType" (they are not methods)
* fix NoSuchMethodError.toString() (update via dart2js sdk impl)
R=vsm@google.com
Review-Url: https://codereview.chromium.org/2962263002 .
Vijay Menon