Create const ints for int8_t and int32_t in jmp assembler (making win64 build...

src/x64/assembler-x64.cc

Index: src/x64/assembler-x64.cc
===================================================================
--- src/x64/assembler-x64.cc	(revision 4405)
+++ src/x64/assembler-x64.cc	(working copy)
@@ -1139,22 +1139,24 @@
   EnsureSpace ensure_space(this);
   last_pc_ = pc_;
   if (L->is_bound()) {
+    const int short_size = sizeof(int8_t);
+    const int long_size = sizeof(int32_t);
     int offs = L->pos() - pc_offset() - 1;
     ASSERT(offs <= 0);
-    if (is_int8(offs - sizeof(int8_t))) {
+    if (is_int8(offs - short_size)) {
       // 1110 1011 #8-bit disp.
       emit(0xEB);
-      emit((offs - sizeof(int8_t)) & 0xFF);
+      emit((offs - short_size) & 0xFF);
     } else {
       // 1110 1001 #32-bit disp.
       emit(0xE9);
-      emitl(offs - sizeof(int32_t));
+      emitl(offs - long_size);
     }
   } else  if (L->is_linked()) {
     // 1110 1001 #32-bit disp.
     emit(0xE9);
     emitl(L->pos());
-    L->link_to(pc_offset() - sizeof(int32_t));
+    L->link_to(pc_offset() - long_size);
   } else {
     // 1110 1001 #32-bit disp.
     ASSERT(L->is_unused());