Ensure TextEditorComponent was resized before asserting on its contents

Previously, we would wait for the next update promise after resizing the 
editor as an indicator of when the resize occurred. Unfortunately, 
resize events are unreliable and may not be emitted right away. This 
could cause the test code to wait for an update promise that was 
unrelated to the resize event (e.g., cursor blinking).

This commit uses a condition-based promise that ensures the rendered 
rows have changed as a result of the resize. This seems to fix the issue 
locally when introducing artificial timeouts in the resize event.

spec/text-editor-component-spec.js

@@ -3297,9 +3297,12 @@ describe('TextEditorComponent', () => {
       // make the editor taller and wider and the same time, ensuring the number
       // of rendered lines is correct.
       setEditorHeightInLines(component, 13);
-      await setEditorWidthInCharacters(component, 50);
-      expect(component.getRenderedStartRow()).toBe(0);
-      expect(component.getRenderedEndRow()).toBe(13);
+      setEditorWidthInCharacters(component, 50);
+      await conditionPromise(
+        () =>
+          component.getRenderedStartRow() === 0 &&
+          component.getRenderedEndRow() === 13
+      );
       expect(component.getScrollHeight()).toBe(
         editor.getScreenLineCount() * component.getLineHeight() +
           getElementHeight(item2) +