Improve type propagation with if-contexts

This works by adding a new instruction (HBoundType) after each `if (a
instanceof ClassA) {}` to bound the type that `a` can take in the True-
dominated blocks.

Change-Id: Iae6a150b353486d4509b0d9b092164675732b90c
diff --git a/compiler/optimizing/code_generator_arm.cc b/compiler/optimizing/code_generator_arm.cc
index 7b0231b..e864ae1 100644
--- a/compiler/optimizing/code_generator_arm.cc
+++ b/compiler/optimizing/code_generator_arm.cc
@@ -3865,5 +3865,17 @@
   DCHECK(!IsLeafMethod());
 }
 
+void LocationsBuilderARM::VisitBoundType(HBoundType* instruction) {
+  // Nothing to do, this should be removed during prepare for register allocator.
+  UNUSED(instruction);
+  LOG(FATAL) << "Unreachable";
+}
+
+void InstructionCodeGeneratorARM::VisitBoundType(HBoundType* instruction) {
+  // Nothing to do, this should be removed during prepare for register allocator.
+  UNUSED(instruction);
+  LOG(FATAL) << "Unreachable";
+}
+
 }  // namespace arm
 }  // namespace art