Fix Win64 compilation.

src/runtime.cc

 // Copyright 2010 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 6847 matching lines @@
     // unoptimized code.
     JavaScriptFrameIterator it;
     JavaScriptFrame* frame = it.frame();
     ASSERT(frame->function() == *function);
     ASSERT(frame->code() == *unoptimized);
     ASSERT(unoptimized->contains(frame->pc()));
 
     // Use linear search of the unoptimized code's stack check table to find
     // the AST id matching the PC.
     Address start = unoptimized->instruction_start();
-    unsigned target_pc_offset = frame->pc() - start;
+    unsigned target_pc_offset = static_cast<unsigned>(frame->pc() - start);
     Address table_cursor = start + unoptimized->stack_check_table_start();
     uint32_t table_length = Memory::uint32_at(table_cursor);
     table_cursor += kIntSize;
     for (unsigned i = 0; i < table_length; ++i) {
       // Table entries are (AST id, pc offset) pairs.
       uint32_t pc_offset = Memory::uint32_at(table_cursor + kIntSize);
       if (pc_offset == target_pc_offset) {
         ast_id = static_cast<int>(Memory::uint32_at(table_cursor));
         break;
       }
@@ skipping 3905 matching lines @@
   } else {
     // Handle last resort GC and make sure to allow future allocations
     // to grow the heap without causing GCs (if possible).
     Counters::gc_last_resort_from_js.Increment();
     Heap::CollectAllGarbage(false);
   }
 }
 
 
 } }  // namespace v8::internal