Add asserts to ensure that we:

src/x64/deoptimizer-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 695 matching lines @@
   __ movq(Operand(rsp, 4 * kPointerSize), arg5);
   __ LoadAddress(arg5, ExternalReference::isolate_address());
   __ movq(Operand(rsp, 5 * kPointerSize), arg5);
 #else
   __ movq(r8, arg5);
   __ LoadAddress(r9, ExternalReference::isolate_address());
 #endif
 
   Isolate* isolate = masm()->isolate();
 
-  __ CallCFunction(ExternalReference::new_deoptimizer_function(isolate), 6);
+  {
+    AllowExternalCallThatCantCauseGC scope(masm());
+    __ CallCFunction(ExternalReference::new_deoptimizer_function(isolate), 6);
+  }
   // Preserve deoptimizer object in register rax and get the input
   // frame descriptor pointer.
   __ movq(rbx, Operand(rax, Deoptimizer::input_offset()));
 
   // Fill in the input registers.
   for (int i = kNumberOfRegisters -1; i >= 0; i--) {
     int offset = (i * kPointerSize) + FrameDescription::registers_offset();
     __ pop(Operand(rbx, offset));
   }
 
@@ skipping 25 matching lines @@
   __ pop(Operand(rdx, 0));
   __ addq(rdx, Immediate(sizeof(intptr_t)));
   __ cmpq(rcx, rsp);
   __ j(not_equal, &pop_loop);
 
   // Compute the output frame in the deoptimizer.
   __ push(rax);
   __ PrepareCallCFunction(2);
   __ movq(arg1, rax);
   __ LoadAddress(arg2, ExternalReference::isolate_address());
-  __ CallCFunction(
-      ExternalReference::compute_output_frames_function(isolate), 2);
+  {
+    AllowExternalCallThatCantCauseGC scope(masm());
+    __ CallCFunction(
+        ExternalReference::compute_output_frames_function(isolate), 2);
+  }
   __ pop(rax);
 
   // Replace the current frame with the output frames.
   Label outer_push_loop, inner_push_loop;
   // Outer loop state: rax = current FrameDescription**, rdx = one past the
   // last FrameDescription**.
   __ movl(rdx, Operand(rax, Deoptimizer::output_count_offset()));
   __ movq(rax, Operand(rax, Deoptimizer::output_offset()));
   __ lea(rdx, Operand(rax, rdx, times_8, 0));
   __ bind(&outer_push_loop);
@@ skipping 64 matching lines @@
   }
   __ bind(&done);
 }
 
 #undef __
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64