Start porting fast typechecks to x64.

runtime/vm/parser.cc

Index: runtime/vm/parser.cc
===================================================================
--- runtime/vm/parser.cc	(revision 7716)
+++ runtime/vm/parser.cc	(working copy)
@@ -236,6 +236,7 @@
 }
 
 
+// For parsing a compilation unit.
 Parser::Parser(const Script& script,
                const Library& library)
     : script_(script),
@@ -256,6 +257,7 @@
 }
 
 
+// For parsing a function.
 Parser::Parser(const Script& script,
                const Function& function,
                intptr_t token_index)
@@ -274,6 +276,9 @@
   ASSERT(!tokens_.IsNull());
   ASSERT(!function.IsNull());
   SetPosition(token_index);
+  if (FLAG_enable_type_checks) {
+    EnsureExpressionTemp();
+  }
 }