Support web, limit position to duration.

example/pubspec.lock

@@ -74,6 +74,11 @@ packages:
     description: flutter
     source: sdk
     version: "0.0.0"
+  flutter_web_plugins:
+    dependency: transitive
+    description: flutter
+    source: sdk
+    version: "0.0.0"
   image:
     dependency: transitive
     description:
@@ -87,7 +92,7 @@ packages:
       path: ".."
       relative: true
     source: path
-    version: "0.0.6"
+    version: "0.1.0"
   matcher:
     dependency: transitive
     description:
@@ -116,13 +121,6 @@ packages:
       url: "https://pub.dartlang.org"
     source: hosted
     version: "1.5.1"
-  pedantic:
-    dependency: transitive
-    description:
-      name: pedantic
-      url: "https://pub.dartlang.org"
-    source: hosted
-    version: "1.8.0+1"
   petitparser:
     dependency: transitive
     description:
@@ -197,7 +195,7 @@ packages:
       name: test_api
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "0.2.11"
+    version: "0.2.14"
   typed_data:
     dependency: transitive
     description: