Revert "Refactor GetIMTIndex"

I need to revert this to get https://android-review.googlesource.com/#/c/244190/ to cleanly revert. Matthew, do you mind rewriting it?

This reverts commit 50706437d8216e41f0fea1e413cda7891324d397.

Change-Id: I5c1435f5dffb46dbb5b613b22adb88c7770304f2
diff --git a/compiler/optimizing/code_generator_arm.cc b/compiler/optimizing/code_generator_arm.cc
index eca9e2c..4fc3b54 100644
--- a/compiler/optimizing/code_generator_arm.cc
+++ b/compiler/optimizing/code_generator_arm.cc
@@ -1901,7 +1901,7 @@
   __ LoadFromOffset(kLoadWord, temp, temp,
         mirror::Class::ImtPtrOffset(kArmPointerSize).Uint32Value());
   uint32_t method_offset = static_cast<uint32_t>(ImTable::OffsetOfElement(
-      invoke->GetImtIndex(), kArmPointerSize));
+      invoke->GetImtIndex() % ImTable::kSize, kArmPointerSize));
   // temp = temp->GetImtEntryAt(method_offset);
   __ LoadFromOffset(kLoadWord, temp, temp, method_offset);
   uint32_t entry_point =
@@ -6783,7 +6783,7 @@
         locations->InAt(0).AsRegister<Register>(),
         mirror::Class::ImtPtrOffset(kArmPointerSize).Uint32Value());
     method_offset = static_cast<uint32_t>(ImTable::OffsetOfElement(
-        instruction->GetIndex(), kArmPointerSize));
+        instruction->GetIndex() % ImTable::kSize, kArmPointerSize));
   }
   __ LoadFromOffset(kLoadWord,
                     locations->Out().AsRegister<Register>(),