web: Add bindings for remaining field APIs

lib/binding_web/test/node-test.js

@@ -116,6 +116,35 @@ describe("Node", () => {
     })
   });
 
+  describe('.childForFieldName()', () => {
+    it('returns null when the node has no children', () => {
+      tree = parser.parse("class A { b() {} }");
+
+      const classNode = tree.rootNode.firstChild;
+      assert.equal(classNode.type, 'class_declaration');
+
+      const classNameNode = classNode.childForFieldName('name');
+      assert.equal(classNameNode.type, 'identifier');
+      assert.equal(classNameNode.text, 'A');
+
+      const bodyNode = classNode.childForFieldName('body');
+      assert.equal(bodyNode.type, 'class_body');
+      assert.equal(bodyNode.text, '{ b() {} }');
+
+      const methodNode = bodyNode.firstNamedChild;
+      assert.equal(methodNode.type, 'method_definition');
+      assert.equal(methodNode.text, 'b() {}');
+
+      const methodNameNode = methodNode.childForFieldName('name');
+      assert.equal(methodNameNode.type, 'property_identifier');
+      assert.equal(methodNameNode.text, 'b');
+
+      const paramsNode = methodNode.childForFieldName('parameters');
+      assert.equal(paramsNode.type, 'formal_parameters');
+      assert.equal(paramsNode.text, '()');
+    });
+  });
+
   describe(".nextSibling and .previousSibling", () => {
     it("returns the node's next and previous sibling", () => {
       tree = parser.parse("x10 + 1000");