MIPS: Fix assertion-fail on cacheflush from generated code.

src/mips/macro-assembler-mips.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 803 matching lines @@
       stack_offset += kDoubleSize;
     }
   }
   addiu(sp, sp, stack_offset);
 }
 
 
 void MacroAssembler::FlushICache(Register address, unsigned instructions) {
   RegList saved_regs = kJSCallerSaved | ra.bit();
   MultiPush(saved_regs);
+  AllowExternalCallThatCantCauseGC scope(this);
 
   // Save to a0 in case address == t0.
   Move(a0, address);
   PrepareCallCFunction(2, t0);
 
   li(a1, instructions * kInstrSize);
   CallCFunction(ExternalReference::flush_icache_function(isolate()), 2);
   MultiPop(saved_regs);
 }
 
@@ skipping 3920 matching lines @@
        opcode == BGTZL);
   opcode = (cond == eq) ? BEQ : BNE;
   instr = (instr & ~kOpcodeMask) | opcode;
   masm_.emit(instr);
 }
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_MIPS