MethodHandles: Implement invoker / exactInvoker.

Accompanies libcore commit 0a72753297b45d08ca33cf7e87888f5fee87f69e.

- Adds callsiteType field to mirror::EmulatedStackFrame.
- Adds unit tests for MethodHandles.invoker /
  MethodHandles.exactInvoker.

Test: art/test/run-test --host 957
Change-Id: Ia27742c80de560a5b38f792bfa97664678cec8ae
diff --git a/runtime/class_linker_test.cc b/runtime/class_linker_test.cc
index 42108d8..80505d1 100644
--- a/runtime/class_linker_test.cc
+++ b/runtime/class_linker_test.cc
@@ -757,6 +757,7 @@
 struct EmulatedStackFrameOffsets : public CheckOffsets<mirror::EmulatedStackFrame> {
   EmulatedStackFrameOffsets() : CheckOffsets<mirror::EmulatedStackFrame>(
       false, "Ldalvik/system/EmulatedStackFrame;") {
+    addOffset(OFFSETOF_MEMBER(mirror::EmulatedStackFrame, callsite_type_), "callsiteType");
     addOffset(OFFSETOF_MEMBER(mirror::EmulatedStackFrame, references_), "references");
     addOffset(OFFSETOF_MEMBER(mirror::EmulatedStackFrame, stack_frame_), "stackFrame");
     addOffset(OFFSETOF_MEMBER(mirror::EmulatedStackFrame, type_), "type");