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/runtime/entrypoints/quick/quick_trampoline_entrypoints.cc b/runtime/entrypoints/quick/quick_trampoline_entrypoints.cc
index 0a70be1..7175d54 100644
--- a/runtime/entrypoints/quick/quick_trampoline_entrypoints.cc
+++ b/runtime/entrypoints/quick/quick_trampoline_entrypoints.cc
@@ -2174,7 +2174,8 @@
   if (LIKELY(interface_method->GetDexMethodIndex() != DexFile::kDexNoIndex)) {
     // If the dex cache already resolved the interface method, look whether we have
     // a match in the ImtConflictTable.
-    ArtMethod* conflict_method = imt->Get(interface_method->GetImtIndex(), sizeof(void*));
+    uint32_t imt_index = interface_method->GetDexMethodIndex();
+    ArtMethod* conflict_method = imt->Get(imt_index % ImTable::kSize, sizeof(void*));
     if (LIKELY(conflict_method->IsRuntimeMethod())) {
       ImtConflictTable* current_table = conflict_method->GetImtConflictTable(sizeof(void*));
       DCHECK(current_table != nullptr);
@@ -2225,8 +2226,8 @@
 
   // We arrive here if we have found an implementation, and it is not in the ImtConflictTable.
   // We create a new table with the new pair { interface_method, method }.
-  uint32_t imt_index = interface_method->GetImtIndex();
-  ArtMethod* conflict_method = imt->Get(imt_index, sizeof(void*));
+  uint32_t imt_index = interface_method->GetDexMethodIndex();
+  ArtMethod* conflict_method = imt->Get(imt_index % ImTable::kSize, sizeof(void*));
   if (conflict_method->IsRuntimeMethod()) {
     ArtMethod* new_conflict_method = Runtime::Current()->GetClassLinker()->AddMethodToConflictTable(
         cls.Get(),
@@ -2237,7 +2238,7 @@
     if (new_conflict_method != conflict_method) {
       // Update the IMT if we create a new conflict method. No fence needed here, as the
       // data is consistent.
-      imt->Set(imt_index,
+      imt->Set(imt_index % ImTable::kSize,
                new_conflict_method,
                sizeof(void*));
     }