All: Improves deletion fail-safe so it is based on percentage of notes deleted. And display warning on sidebar.

ReactNativeClient/lib/shim-init-node.js

@@ -362,6 +362,10 @@ function shimInit() {
 		bridge().openExternal(url);
 	};
 
+	shim.isTestingEnv = () => {
+		return process.env.NODE_ENV === 'testing';
+	};
+
 	shim.waitForFrame = () => {};
 }