Fix crash in optimized code caused by missing IC data.

runtime/vm/intrinsifier_x64.cc

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/globals.h"  // Needed here to get TARGET_ARCH_X64.
 #if defined(TARGET_ARCH_X64)
 
 #include "vm/intrinsifier.h"
 
 #include "vm/assembler.h"
@@ skipping 1448 matching lines @@
   // Get length.
   __ movq(RAX, Address(RSP, + 1 * kWordSize));  // String object.
   __ movq(RAX, FieldAddress(RAX, String::length_offset()));
   __ cmpq(RAX, Immediate(Smi::RawValue(0)));
   __ j(EQUAL, &is_true, Assembler::kNearJump);
   __ LoadObject(RAX, Bool::False());
   __ ret();
   __ Bind(&is_true);
   __ LoadObject(RAX, Bool::True());
   __ ret();
-  return true;
+  return false;
 }
 
 
 bool Intrinsifier::OneByteString_getHashCode(Assembler* assembler) {
   Label compute_hash;
   __ movq(RBX, Address(RSP, + 1 * kWordSize));  // OneByteString object.
   __ movq(RAX, FieldAddress(RBX, String::hash_offset()));
   __ cmpq(RAX, Immediate(0));
   __ j(EQUAL, &compute_hash, Assembler::kNearJump);
   __ ret();
@@ skipping 207 matching lines @@
   __ Bind(&fall_through);
   return false;
 }
 
 
 #undef __
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_X64