Improve error messages and add many corrections

pkg/analyzer/lib/src/generated/parser.dart

Index: pkg/analyzer/lib/src/generated/parser.dart
diff --git a/pkg/analyzer/lib/src/generated/parser.dart b/pkg/analyzer/lib/src/generated/parser.dart
index 1f51d664820f882b1fbf97cac4a7bc0430b426c1..7e913103634855449dd58c091f34a7a6a2990b6f 100644
--- a/pkg/analyzer/lib/src/generated/parser.dart
+++ b/pkg/analyzer/lib/src/generated/parser.dart
@@ -6430,7 +6430,8 @@ class Parser {
         if (leftSquareBracket == null) {
           if (leftCurlyBracket != null) {
             _reportErrorForCurrentToken(
-                ParserErrorCode.WRONG_TERMINATOR_FOR_PARAMETER_GROUP, ["}"]);
+                ParserErrorCode.WRONG_TERMINATOR_FOR_PARAMETER_GROUP,
+                ['}', ']']);
             rightCurlyBracket = rightSquareBracket;
             rightSquareBracket = null;
           } else {
@@ -6445,7 +6446,8 @@ class Parser {
         if (leftCurlyBracket == null) {
           if (leftSquareBracket != null) {
             _reportErrorForCurrentToken(
-                ParserErrorCode.WRONG_TERMINATOR_FOR_PARAMETER_GROUP, ["]"]);
+                ParserErrorCode.WRONG_TERMINATOR_FOR_PARAMETER_GROUP,
+                [']', '}']);
             rightSquareBracket = rightCurlyBracket;
             rightCurlyBracket = null;
           } else {
@@ -7842,7 +7844,7 @@ class Parser {
   }
 
   /**
-   * Validate that the given set of [modifiers] is appropriate for a class and
+   * Validate that the given set of [modifiers] is appropriate for an enum and
    * return the 'abstract' keyword if there is one.
    */
   void _validateModifiersForEnum(Modifiers modifiers) {