Introduces MethodInvocation.staticInvokeType to track the type of this invocation. This provides a natural place to store the instantiated generic function type. We then use this type when we are computing corresponding parameters or return types. As a result we do not need FunctionMember, and some of the code around generics becomes simpler/more uniform.
This approach should be a straightforward way to add support for generics in FunctionExpressionInvocation, in a follow up (see issue #25175).
Also renames "boundTypeParameters" to "typeFormals". "formals" and "actuals" is a pretty common way to describe these, I'm not sure why I didn't think of that better name originally. :)
Also removes broken ParameterMember.== that I had added in a previous CL. And the broken FunctionTypeImpl.originalFunction/instantiatedTypeArguments getters.
Finally, this fixes#23252 in the process of adding this. The return type of a "call" method was not being statically analyzed if the target was a VariableElement.
R=brianwilkerson@google.com, leafp@google.com
Review URL: https://codereview.chromium.org/1568643002 .
John Messerly
924f2f97b7