Fixes Windows compiler warning about unary minus applied to unsigned int.

src/regexp-macro-assembler-ia32.cc

 // Copyright 2008 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 647 matching lines @@
   __ mov(edx, Operand(edx, 0));
   // Add start to length to complete esi setup.
   __ add(esi, Operand(edx));
   if (num_saved_registers_ > 0) {
     // Fill saved registers with initial value = start offset - 1
     // Fill in stack push order, to avoid accessing across an unwritten
     // page (a problem on Windows).
     const int kRegisterZeroEBPOffset = -1;
     __ mov(ecx, kRegisterZeroEBPOffset);
     // Set eax to address of char before start of input.
-    __ lea(eax, Operand(edi, -char_size()));
+    __ lea(eax, Operand(edi, -static_cast<int32_t>(char_size())));
     Label init_loop;
     __ bind(&init_loop);
     __ mov(Operand(ebp, ecx, times_4, +0), eax);
     __ sub(Operand(ecx), Immediate(1));
     __ cmp(ecx, -num_saved_registers_);
     __ j(greater_equal, &init_loop);
   }
   // Ensure that we have written to each stack page. Skipping a page on
   // Windows can cause segmentation faults. Assuming page size is 4k.
   const int kPageSize = 4096;
@@ skipping 514 matching lines @@
 
 
 void RegExpMacroAssemblerIA32::LoadConstantBufferAddress(Register reg,
                                                          ArraySlice* buffer) {
   __ mov(reg, buffer->array());
   __ add(Operand(reg), Immediate(buffer->base_offset()));
 }
 
 #undef __
 }}  // namespace v8::internal