[web] Fix inability to type in text fields in iOS (flutter#27563)

lib/web_ui/lib/src/engine/text_editing/text_editing.dart

@@ -1133,13 +1133,23 @@ class IOSTextEditingStrategy extends GloballyPositionedTextEditingStrategy {
 
     _addTapListener();
 
-    // On iOS, blur is trigerred if the virtual keyboard is closed or the
-    // browser is sent to background or the browser tab is changed.
+    // On iOS, blur is trigerred in the following cases:
     //
-    // Since in all these cases, the connection needs to be closed,
-    // [domRenderer.windowHasFocus] is not checked in [IOSTextEditingStrategy].
+    // 1. The browser app is sent to the background (or the tab is changed). In
+    //    this case, the window loses focus (see [domRenderer.windowHasFocus]),
+    //    so we close the input connection with the framework.
+    // 2. The user taps on another focusable element. In this case, we refocus
+    //    the input field and wait for the framework to manage the focus change.
+    // 3. The virtual keyboard is closed by tapping "done". We can't detect this
+    //    programmatically, so we end up refocusing the input field. This is
+    //    okay because the virtual keyboard will hide, and as soon as the user
+    //    taps the text field again, the virtual keyboard will come up.
     subscriptions.add(activeDomElement.onBlur.listen((_) {
-      owner.sendTextConnectionClosedToFrameworkIfAny();
+      if (domRenderer.windowHasFocus) {
+        activeDomElement.focus();
+      } else {
+        owner.sendTextConnectionClosedToFrameworkIfAny();
+      }
     }));
   }
 

lib/web_ui/test/text_editing_test.dart

@@ -584,24 +584,12 @@ void testMain() {
       // DOM element is blurred.
       textEditing!.strategy.domElement!.blur();
 
-      // For ios-safari the connection is closed.
-      if (browserEngine == BrowserEngine.webkit &&
-          operatingSystem == OperatingSystem.iOs) {
-        expect(spy.messages, hasLength(1));
-        expect(spy.messages[0].channel, 'flutter/textinput');
-        expect(
-            spy.messages[0].methodName, 'TextInputClient.onConnectionClosed');
-        await Future<void>.delayed(Duration.zero);
-        // DOM element loses the focus.
-        expect(defaultTextEditingRoot.activeElement, null);
-      } else {
-        // No connection close message sent.
-        expect(spy.messages, hasLength(0));
-        await Future<void>.delayed(Duration.zero);
-        // DOM element still keeps the focus.
-        expect(defaultTextEditingRoot.activeElement,
-            textEditing!.strategy.domElement);
-      }
+      // No connection close message sent.
+      expect(spy.messages, hasLength(0));
+      await Future<void>.delayed(Duration.zero);
+      // DOM element still keeps the focus.
+      expect(defaultTextEditingRoot.activeElement,
+          textEditing!.strategy.domElement);
     },
         // TODO(nurhan): https://github.com/flutter/flutter/issues/50769
         skip: browserEngine == BrowserEngine.edge);