Fix more strong mode errors in analyzer

pkg/analyzer/lib/src/task/html.dart

Index: pkg/analyzer/lib/src/task/html.dart
diff --git a/pkg/analyzer/lib/src/task/html.dart b/pkg/analyzer/lib/src/task/html.dart
index ae1fb0dfda3d7077efe8b4a0a4b1897e1974549e..257567764be06baa4dda3b18db1fcaf76b96226e 100644
--- a/pkg/analyzer/lib/src/task/html.dart
+++ b/pkg/analyzer/lib/src/task/html.dart
@@ -166,7 +166,7 @@ class DartScriptsTask extends SourceBasedAnalysisTask {
    * input descriptors describing those inputs for a task with the
    * given [target].
    */
-  static Map<String, TaskInput> buildInputs(Source target) {
+  static Map<String, TaskInput> buildInputs(AnalysisTarget target) {
     return <String, TaskInput>{DOCUMENT_INPUT: HTML_DOCUMENT.of(target)};
   }
 
@@ -237,7 +237,7 @@ class HtmlErrorsTask extends SourceBasedAnalysisTask {
    * input descriptors describing those inputs for a task with the
    * given [target].
    */
-  static Map<String, TaskInput> buildInputs(Source target) {
+  static Map<String, TaskInput> buildInputs(AnalysisTarget target) {
     EnginePlugin enginePlugin = AnalysisEngine.instance.enginePlugin;
     Map<String, TaskInput> inputs = <String, TaskInput>{
       DART_ERRORS_INPUT: DART_SCRIPTS.of(target).toListOf(DART_ERRORS)
@@ -342,7 +342,7 @@ class ParseHtmlTask extends SourceBasedAnalysisTask {
    * input descriptors describing those inputs for a task with the given
    * [source].
    */
-  static Map<String, TaskInput> buildInputs(Source source) {
+  static Map<String, TaskInput> buildInputs(AnalysisTarget source) {
     return <String, TaskInput>{CONTENT_INPUT_NAME: CONTENT.of(source)};
   }