[macos] Move TextInputPlugin outside of visible area (#39031)

* [macos] Move TextInputPlugin outside of visible area

* Make plugin empty and add test

Author: knopp

shell/platform/darwin/macos/framework/Source/FlutterTextInputPlugin.mm

@@ -245,8 +245,9 @@ @implementation FlutterTextInputPlugin {
 }
 
 - (instancetype)initWithViewController:(FlutterViewController*)viewController {
-  // The view needs a non-zero frame.
-  self = [super initWithFrame:NSMakeRect(0, 0, 1, 1)];
+  // The view needs an empty frame otherwise it is visible on dark background.
+  // https://github.com/flutter/flutter/issues/118504
+  self = [super initWithFrame:NSZeroRect];
   if (self != nil) {
     _flutterViewController = viewController;
     _channel = [FlutterMethodChannel methodChannelWithName:kTextInputChannel

shell/platform/darwin/macos/framework/Source/FlutterTextInputPluginTest.mm

@@ -1532,4 +1532,20 @@ - (bool)testSelectorsAreForwardedToFramework {
   ASSERT_FALSE(window.firstResponder == viewController.textInputPlugin);
 }
 
+TEST(FlutterTextInputPluginTest, HasZeroSize) {
+  id engineMock = OCMClassMock([FlutterEngine class]);
+  id binaryMessengerMock = OCMProtocolMock(@protocol(FlutterBinaryMessenger));
+  OCMStub(  // NOLINT(google-objc-avoid-throwing-exception)
+      [engineMock binaryMessenger])
+      .andReturn(binaryMessengerMock);
+  FlutterViewController* viewController = [[FlutterViewController alloc] initWithEngine:engineMock
+                                                                                nibName:@""
+                                                                                 bundle:nil];
+
+  FlutterTextInputPlugin* plugin =
+      [[FlutterTextInputPlugin alloc] initWithViewController:viewController];
+
+  ASSERT_TRUE(NSIsEmptyRect(plugin.frame));
+}
+
 }  // namespace flutter::testing