Fix uninitialized fields in the BinaryOperation ast node.

R=jkummerow@chromium.org, svenpanne@chromium.org
BUG=chromium:429194
LOG=n

Review URL: https://codereview.chromium.org/701533002

Cr-Commit-Position: refs/heads/master@{#25077}
git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@25077 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/ast.h

@@ -2094,6 +2094,8 @@ class BinaryOperation FINAL : public Expression {
                   Expression* right, int pos)
       : Expression(zone, pos),
         op_(static_cast<byte>(op)),
+        has_fixed_right_arg_(false),
+        fixed_right_arg_value_(0),
         left_(left),
         right_(right) {
     DCHECK(Token::IsBinaryOp(op));