Fix #967 by overriding the updateWidth method in FieldImage blocks to be a no-op. FieldImage fields should not change size after the width is set in init. The updateWidth and, therefore, getCachedWidth is now being called by BlockSvg renderFields_ (see commit d55d9cbd9f). IIUC, updateWidth/getCachedWidth was only called from render before which is overridden in FieldImage to be a no-op already. (#979)

core/field_image.js

@@ -153,3 +153,10 @@ Blockly.FieldImage.prototype.setText = function(alt) {
 Blockly.FieldImage.prototype.render_ = function() {
   // NOP
 };
+/**
+ * Images are fixed width, no need to update.
+ * @private
+ */
+Blockly.FieldImage.prototype.updateWidth = function() {
+ // NOP
+};