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_mips.cc b/compiler/optimizing/code_generator_mips.cc
index d5bad28..c8e927d 100644
--- a/compiler/optimizing/code_generator_mips.cc
+++ b/compiler/optimizing/code_generator_mips.cc
@@ -3720,7 +3720,7 @@
   __ LoadFromOffset(kLoadWord, temp, temp,
       mirror::Class::ImtPtrOffset(kMipsPointerSize).Uint32Value());
   uint32_t method_offset = static_cast<uint32_t>(ImTable::OffsetOfElement(
-      invoke->GetImtIndex(), kMipsPointerSize));
+      invoke->GetImtIndex() % ImTable::kSize, kMipsPointerSize));
   // temp = temp->GetImtEntryAt(method_offset);
   __ LoadFromOffset(kLoadWord, temp, temp, method_offset);
   // T9 = temp->GetEntryPoint();
@@ -5169,7 +5169,7 @@
                       locations->InAt(0).AsRegister<Register>(),
                       mirror::Class::ImtPtrOffset(kMipsPointerSize).Uint32Value());
     method_offset = static_cast<uint32_t>(ImTable::OffsetOfElement(
-        instruction->GetIndex(), kMipsPointerSize));
+        instruction->GetIndex() % ImTable::kSize, kMipsPointerSize));
   }
   __ LoadFromOffset(kLoadWord,
                     locations->Out().AsRegister<Register>(),