Quick Fix for adding 'async' to fix invalid 'await'.

pkg/analysis_server/lib/src/services/correction/fix_internal.dart

Index: pkg/analysis_server/lib/src/services/correction/fix_internal.dart
diff --git a/pkg/analysis_server/lib/src/services/correction/fix_internal.dart b/pkg/analysis_server/lib/src/services/correction/fix_internal.dart
index c46ee05bf9cd47c09a9c2318bdd6e25849acff74..cc4311647f8e294f6e5c0d6f7c63ed2400ac678b 100644
--- a/pkg/analysis_server/lib/src/services/correction/fix_internal.dart
+++ b/pkg/analysis_server/lib/src/services/correction/fix_internal.dart
@@ -198,12 +198,15 @@ class FixProcessor {
       _addFix_undefinedClass_useSimilar();
     }
     if (errorCode == StaticWarningCode.UNDEFINED_IDENTIFIER) {
-      _addFix_createField();
-      _addFix_createGetter();
-      _addFix_createFunction_forFunctionType();
-      _addFix_importLibrary_withType();
-      _addFix_importLibrary_withTopLevelVariable();
-      _addFix_createLocalVariable();
+      bool isAsync = _addFix_addAsync();
+      if (!isAsync) {
+        _addFix_createField();
+        _addFix_createGetter();
+        _addFix_createFunction_forFunctionType();
+        _addFix_importLibrary_withType();
+        _addFix_importLibrary_withTopLevelVariable();
+        _addFix_createLocalVariable();
+      }
     }
     if (errorCode == StaticTypeWarningCode.INSTANCE_ACCESS_TO_STATIC_MEMBER) {
       _addFix_useStaticAccess_method();
@@ -264,6 +267,22 @@ class FixProcessor {
     exitPosition = null;
   }
 
+  /**
+   * Returns `true` if the `async` proposal was added.
+   */
+  bool _addFix_addAsync() {
+    AstNode node = this.node;
+    if (_isAwaitNode()) {
+      FunctionBody body = node.getAncestor((n) => n is FunctionBody);
+      if (body.keyword == null) {
+        _addReplaceEdit(rf.rangeStartLength(body, 0), 'async ');
+        _addFix(FixKind.ADD_ASYNC, []);
+        return true;
+      }
+    }
+    return false;
+  }
+
   void _addFix_boolInsteadOfBoolean() {
     SourceRange range = rf.rangeError(error);
     _addReplaceEdit(range, 'bool');
@@ -1164,6 +1183,9 @@ class FixProcessor {
 
   void _addFix_insertSemicolon() {
     if (error.message.contains("';'")) {
+      if (_isAwaitNode()) {
+        return;
+      }
       int insertOffset = error.offset + error.length;
       _addInsertEdit(insertOffset, ';');
       _addFix(FixKind.INSERT_SEMICOLON, []);
@@ -2065,6 +2087,11 @@ class FixProcessor {
     return method != null && method.isStatic;
   }
 
+  bool _isAwaitNode() {
+    AstNode node = this.node;
+    return node is SimpleIdentifier && node.name == 'await';
+  }
+
   _ConstructorLocation
       _prepareNewConstructorLocation(ClassDeclaration classDeclaration) {
     List<ClassMember> members = classDeclaration.members;