Remove ArtCode.

- Instead use OatQuickMethodHeader.
- Various cleanups now that we don't have all those
  ArtMethod -> ArtCode -> OatQuickMethodHeader indirections.

As a consequence of this cleanup, exception handling got a bit
faster.

ParserCombinators benchmark (exception intensive) on x64: (lower is better)
Before:
ParserCombinators(RunTime): 1062500.0 us.
After:
ParserCombinators(RunTime): 833000.0 us.

Change-Id: Idac917b6f1b0dc254ad68fb3781cd61bccadb0f3
diff --git a/runtime/fault_handler.cc b/runtime/fault_handler.cc
index 5b31b3a..52ccbee 100644
--- a/runtime/fault_handler.cc
+++ b/runtime/fault_handler.cc
@@ -20,10 +20,10 @@
 #include <sys/mman.h>
 #include <sys/ucontext.h>
 
-#include "art_code.h"
 #include "art_method-inl.h"
 #include "base/stl_util.h"
 #include "mirror/class.h"
+#include "oat_quick_method_header.h"
 #include "sigchain.h"
 #include "thread-inl.h"
 #include "verify_object-inl.h"
@@ -360,17 +360,17 @@
     return false;
   }
 
-  ArtCode art_code(method_obj);
+  const OatQuickMethodHeader* method_header = method_obj->GetOatQuickMethodHeader(return_pc);
 
   // We can be certain that this is a method now.  Check if we have a GC map
   // at the return PC address.
   if (true || kIsDebugBuild) {
     VLOG(signals) << "looking for dex pc for return pc " << std::hex << return_pc;
     uint32_t sought_offset = return_pc -
-        reinterpret_cast<uintptr_t>(art_code.GetQuickOatEntryPoint(sizeof(void*)));
+        reinterpret_cast<uintptr_t>(method_header->GetEntryPoint());
     VLOG(signals) << "pc offset: " << std::hex << sought_offset;
   }
-  uint32_t dexpc = art_code.ToDexPc(return_pc, false);
+  uint32_t dexpc = method_header->ToDexPc(method_obj, return_pc, false);
   VLOG(signals) << "dexpc: " << dexpc;
   return !check_dex_pc || dexpc != DexFile::kDexNoIndex;
 }