Add typing for Int32MulHigh.

TBR=rossberg@chromium.org
BUG=

Review URL: https://codereview.chromium.org/656803003

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@24602 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/compiler/typer.cc

@@ -931,6 +931,11 @@ Bounds Typer::Visitor::TypeInt32Mul(Node* node) {
 }
 
 
+Bounds Typer::Visitor::TypeInt32MulHigh(Node* node) {
+  return Bounds(Type::Integral32());
+}
+
+
 Bounds Typer::Visitor::TypeInt32Div(Node* node) {
   return Bounds(Type::Integral32());
 }