Refactor GetIMTIndex

This allows us to more easily maintain and experiment with
interface method table indexing and hashing.

Change-Id: I719920fae7490dcedcda7c1c36db225c2b8b16df
diff --git a/compiler/optimizing/code_generator_arm.cc b/compiler/optimizing/code_generator_arm.cc
index 4fc3b54..eca9e2c 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() % ImTable::kSize, kArmPointerSize));
+      invoke->GetImtIndex(), 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() % ImTable::kSize, kArmPointerSize));
+        instruction->GetIndex(), kArmPointerSize));
   }
   __ LoadFromOffset(kLoadWord,
                     locations->Out().AsRegister<Register>(),