Avoid including undefined in return value of Query.matches

Fixes #932

lib/binding_web/test/query-test.js

@@ -81,6 +81,32 @@ describe("Query", () => {
         { pattern: 0, captures: [{ name: "element", text: "g" }] },
       ]);
     });
+
+    it("handles predicates that compare the text of capture to literal strings", () => {
+      tree = parser.parse(`
+        giraffe(1, 2, []);
+        helment([false]);
+        goat(false);
+        gross(3, []);
+        hiccup([]);
+        gaff(5);
+      `);
+
+      // Find all calls to functions beginning with 'g', where one argument
+      // is an array literal.
+      query = JavaScript.query(`
+        (call_expression
+          function: (identifier) @name
+          arguments: (arguments (array))
+          (#match? @name "^g"))
+      `);
+
+      const matches = query.matches(tree.rootNode);
+      assert.deepEqual(formatMatches(matches), [
+        { pattern: 0, captures: [{name: "name", text: "giraffe" }] },
+        { pattern: 0, captures: [{name: "name", text: "gross" }] },
+      ]);
+    });
   });
 
   describe(".captures", () => {