Fix opmitized external array access for compound assignments

src/x64/lithium-codegen-x64.cc

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 2293 matching lines @@
         break;
       case kExternalUnsignedIntArray:
         __ movl(result, Operand(external_pointer, key, times_4, 0));
         __ testl(result, result);
         // TODO(danno): we could be more clever here, perhaps having a special
         // version of the stub that detects if the overflow case actually
         // happens, and generate code that returns a double rather than int.
         DeoptimizeIf(negative, instr->environment());
         break;
       case kExternalFloatArray:
+      default:
         UNREACHABLE();
         break;
     }
   }
 }
 
 
 void LCodeGen::DoLoadKeyedGeneric(LLoadKeyedGeneric* instr) {
   ASSERT(ToRegister(instr->object()).is(rdx));
   ASSERT(ToRegister(instr->key()).is(rax));
@@ skipping 633 matching lines @@
         break;
       case kExternalShortArray:
       case kExternalUnsignedShortArray:
         __ movw(Operand(external_pointer, key, times_2, 0), value);
         break;
       case kExternalIntArray:
       case kExternalUnsignedIntArray:
         __ movl(Operand(external_pointer, key, times_4, 0), value);
         break;
       case kExternalFloatArray:
+      default:
         UNREACHABLE();
         break;
     }
   }
 }
 
 
 void LCodeGen::DoBoundsCheck(LBoundsCheck* instr) {
   if (instr->length()->IsRegister()) {
     __ cmpq(ToRegister(instr->index()), ToRegister(instr->length()));
@@ skipping 963 matching lines @@
   RegisterEnvironmentForDeoptimization(environment);
   ASSERT(osr_pc_offset_ == -1);
   osr_pc_offset_ = masm()->pc_offset();
 }
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64