[web] Migrate Flutter Web to JS static interop - 1.

This is the first CL in a series of cls to migrate Flutter Web to JS
static interop.

Author: joshualitt

lib/web_ui/lib/src/engine/configuration.dart

@@ -162,8 +162,10 @@ external JsFlutterConfiguration? get _jsConfiguration;
 
 /// The JS bindings for the object that's set as `window.flutterConfiguration`.
 @JS()
-@anonymous
-class JsFlutterConfiguration {
+@staticInterop
+class JsFlutterConfiguration {}
+
+extension JsFlutterConfigurationExtension on JsFlutterConfiguration {
   external String? get canvasKitBaseUrl;
   external bool? get canvasKitForceCpuOnly;
   external bool? get debugShowSemanticsNodes;

lib/web_ui/pubspec.yaml

@@ -6,7 +6,7 @@ environment:
   sdk: ">=2.12.0-0 <3.0.0"
 
 dependencies:
-  js: 0.6.3
+  js: 0.6.4
   meta: 1.3.0
 
 dev_dependencies:

web_sdk/web_engine_tester/pubspec.yaml

@@ -5,7 +5,7 @@ environment:
   sdk: ">=2.12.0-0 <3.0.0"
 
 dependencies:
-  js: 0.6.3
+  js: 0.6.4
   stream_channel: 2.1.0
   test: 1.17.7
   webkit_inspection_protocol: 1.0.0

web_sdk/web_test_utils/pubspec.yaml

@@ -8,7 +8,7 @@ dependencies:
   collection: 1.15.0
   crypto: 3.0.1
   image: 3.0.1
-  js: 0.6.3
+  js: 0.6.4
   meta: 1.3.0
   path: 1.8.0
   process: 4.2.3