Upgrade field text input to use new serialization

core/field_textinput.js

@@ -178,6 +178,26 @@ Blockly.FieldTextInput.prototype.initView = function() {
   this.createTextElement_();
 };
 
+/**
+ * Saves this field's value.
+ * @return {string} The text value held by this field.
+ * @override
+ * @package
+ */
+Blockly.FieldTextInput.prototype.saveState = function() {
+  return this.value_;
+};
+
+/**
+ * Sets the field's value based on the given state.
+ * @param {*} state The state to apply to the text input field.
+ * @override
+ * @package
+ */
+Blockly.FieldTextInput.prototype.loadState = function(state) {
+  this.setValue(state);
+};
+
 /**
  * Ensure that the input value casts to a valid string.
  * @param {*=} opt_newValue The input value.

tests/mocha/field_textinput_test.js

@@ -215,4 +215,27 @@ suite('Text Input Fields', function() {
       });
     });
   });
+
+  suite('Serialization', function() {
+    setup(function() {
+      this.workspace = new Blockly.Workspace();
+      defineRowBlock();
+
+      this.assertValue = (value) => {
+        const block = this.workspace.newBlock('row_block');
+        const field = new Blockly.FieldTextInput(value);
+        block.getInput('INPUT').appendField(field, 'TEXT');
+        const jso = Blockly.serialization.blocks.save(block);
+        chai.assert.deepEqual(jso['fields'], {'TEXT': value});
+      };
+    });
+
+    teardown(function() {
+      workspaceTeardown.call(this, this.workspace);
+    });
+
+    test('Simple', function() {
+      this.assertValue('test text');
+    });
+  });
 });