Simplify IA32 code generator API.

src/ast.h

Index: src/ast.h
diff --git a/src/ast.h b/src/ast.h
index 252c8f8c82f7d0a4fa789c0d0f9bd9c4bc905cfb..c6194ebe009de1eaf525479727f867cfe79947d5 100644
--- a/src/ast.h
+++ b/src/ast.h
@@ -1369,7 +1369,13 @@ class BinaryOperation: public Expression {
     ASSERT(Token::IsBinaryOp(op));
   }
 
-  BinaryOperation(BinaryOperation* other, Expression* left, Expression* right);
+  // Construct a binary operation with a given operator and left and right
+  // subexpressions.  The rest of the expression state is copied from
+  // another expression.
+  BinaryOperation(Expression* other,
+                  Token::Value op,
+                  Expression* left,
+                  Expression* right);
 
   virtual void Accept(AstVisitor* v);