Clean up OatQuickMethodHeader after Quick removal.

This reduces the size of the pre-header by 8 bytes, reducing
oat file size and mmapped .text section size. The memory
needed to store a CompiledMethod by dex2oat is also reduced,
for 32-bit dex2oat by 8B and for 64-bit dex2oat by 16B. The
aosp_flounder-userdebug 32-bit and 64-bit boot.oat are each
about 1.1MiB smaller.

Disable the broken StubTest.IMT, b/27991555 .

Change-Id: I05fe45c28c8ffb7a0fa8b1117b969786748b1039
diff --git a/runtime/entrypoints/entrypoint_utils.cc b/runtime/entrypoints/entrypoint_utils.cc
index e46576e..197caa1 100644
--- a/runtime/entrypoints/entrypoint_utils.cc
+++ b/runtime/entrypoints/entrypoint_utils.cc
@@ -272,19 +272,19 @@
   if (LIKELY(caller_pc != reinterpret_cast<uintptr_t>(GetQuickInstrumentationExitPc()))) {
     if (outer_method != nullptr) {
       const OatQuickMethodHeader* current_code = outer_method->GetOatQuickMethodHeader(caller_pc);
-      if (current_code->IsOptimized()) {
-        uintptr_t native_pc_offset = current_code->NativeQuickPcOffset(caller_pc);
-        CodeInfo code_info = current_code->GetOptimizedCodeInfo();
-        CodeInfoEncoding encoding = code_info.ExtractEncoding();
-        StackMap stack_map = code_info.GetStackMapForNativePcOffset(native_pc_offset, encoding);
-        DCHECK(stack_map.IsValid());
-        if (stack_map.HasInlineInfo(encoding.stack_map_encoding)) {
-          InlineInfo inline_info = code_info.GetInlineInfoOf(stack_map, encoding);
-          caller = GetResolvedMethod(outer_method,
-                                     inline_info,
-                                     encoding.inline_info_encoding,
-                                     inline_info.GetDepth(encoding.inline_info_encoding) - 1);
-        }
+      DCHECK(current_code != nullptr);
+      DCHECK(current_code->IsOptimized());
+      uintptr_t native_pc_offset = current_code->NativeQuickPcOffset(caller_pc);
+      CodeInfo code_info = current_code->GetOptimizedCodeInfo();
+      CodeInfoEncoding encoding = code_info.ExtractEncoding();
+      StackMap stack_map = code_info.GetStackMapForNativePcOffset(native_pc_offset, encoding);
+      DCHECK(stack_map.IsValid());
+      if (stack_map.HasInlineInfo(encoding.stack_map_encoding)) {
+        InlineInfo inline_info = code_info.GetInlineInfoOf(stack_map, encoding);
+        caller = GetResolvedMethod(outer_method,
+                                   inline_info,
+                                   encoding.inline_info_encoding,
+                                   inline_info.GetDepth(encoding.inline_info_encoding) - 1);
       }
     }
     if (kIsDebugBuild && do_caller_check) {