Fix warnings on Win64.

src/ic.cc

Index: src/ic.cc
diff --git a/src/ic.cc b/src/ic.cc
index c12dba7bb07979768399e0ada9333d45ad098c56..2779356c0e3797f9a9cee6df8236da530ec08f57 100644
--- a/src/ic.cc
+++ b/src/ic.cc
@@ -126,7 +126,8 @@ Address IC::OriginalCodeAddress() {
   // Return the address in the original code. This is the place where
   // the call which has been overwritten by the DebugBreakXXX resides
   // and the place where the inline cache system should look.
-  int delta = original_code->instruction_start() - code->instruction_start();
+  intptr_t delta =
+      original_code->instruction_start() - code->instruction_start();
   return addr + delta;
 }
 #endif