class_linker: Add support for resolving method types.

- Add a new fixed size dex cache array for resolved method types.
  The size of this array is set to 1024.
- Also introduces a new runtime flag that controls this feature.

Test: make test-art-host
Bug: 30550796

Change-Id: I147b33398d71ee21f2e91b418d3700d4630801ff
diff --git a/cmdline/cmdline_types.h b/cmdline/cmdline_types.h
index b74e588..b229be4 100644
--- a/cmdline/cmdline_types.h
+++ b/cmdline/cmdline_types.h
@@ -775,6 +775,8 @@
       existing = existing | ExperimentalFlags::kAgents;
     } else if (option == "runtime-plugins") {
       existing = existing | ExperimentalFlags::kRuntimePlugins;
+    } else if (option == "method-handles") {
+      existing = existing | ExperimentalFlags::kMethodHandles;
     } else {
       return Result::Failure(std::string("Unknown option '") + option + "'");
     }