Fix crash in observatory: stub code do not have inlined intervals information.

runtime/vm/stub_code_arm64.cc

 // Copyright (c) 2014, 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"
 #if defined(TARGET_ARCH_ARM64)
 
 #include "vm/assembler.h"
 #include "vm/code_generator.h"
 #include "vm/compiler.h"
@@ skipping 1243 matching lines @@
       R7, func_reg, Function::usage_counter_offset(), kNoPP, kWord);
 }
 
 
 // Loads function into 'temp_reg'.
 void StubCode::GenerateUsageCounterIncrement(Assembler* assembler,
                                              Register temp_reg) {
   Register ic_reg = R5;
   Register func_reg = temp_reg;
   ASSERT(temp_reg == R6);
+  __ Comment("Increment function counter");
   __ LoadFieldFromOffset(func_reg, ic_reg, ICData::owner_offset(), kNoPP);
   __ LoadFieldFromOffset(
       R7, func_reg, Function::usage_counter_offset(), kNoPP, kWord);
   __ AddImmediate(R7, R7, 1, kNoPP);
   __ StoreFieldToOffset(
       R7, func_reg, Function::usage_counter_offset(), kNoPP, kWord);
 }
 
 
 // Note: R5 must be preserved.
@@ skipping 822 matching lines @@
   const Register right = R0;
   __ LoadFromOffset(left, SP, 1 * kWordSize, kNoPP);
   __ LoadFromOffset(right, SP, 0 * kWordSize, kNoPP);
   GenerateIdenticalWithNumberCheckStub(assembler, left, right, temp);
   __ ret();
 }
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_ARM64