Fix build failure on Win64 since r14458.

src/runtime.cc

 // Copyright 2012 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 2462 matching lines @@
     for (int i = 0; i < operands_count; i++) {
       operand_stack->set(i, frame->GetOperand(i));
     }
     generator_object->set_operand_stack(operand_stack);
   }
 
   // Set continuation down here to avoid side effects if the operand stack
   // allocation fails.
   intptr_t offset = frame->pc() - function->code()->instruction_start();
   ASSERT(offset > 0 && Smi::IsValid(offset));
-  generator_object->set_continuation(offset);
+  generator_object->set_continuation(static_cast<int>(offset));
 
   // It's possible for the context to be other than the initial context even if
   // there is no stack handler active.  For example, this is the case in the
   // body of a "with" statement.  Therefore we always save the context.
   generator_object->set_context(Context::cast(frame->context()));
 
   // The return value is the hole for a suspend return, and anything else for a
   // resume return.
   return isolate->heap()->the_hole_value();
 }
@@ skipping 10892 matching lines @@
     // Handle last resort GC and make sure to allow future allocations
     // to grow the heap without causing GCs (if possible).
     isolate->counters()->gc_last_resort_from_js()->Increment();
     isolate->heap()->CollectAllGarbage(Heap::kNoGCFlags,
                                        "Runtime::PerformGC");
   }
 }
 
 
 } }  // namespace v8::internal