Add parser support for covariant parameters

pkg/analyzer/lib/src/dart/error/syntactic_errors.dart

Index: pkg/analyzer/lib/src/dart/error/syntactic_errors.dart
diff --git a/pkg/analyzer/lib/src/dart/error/syntactic_errors.dart b/pkg/analyzer/lib/src/dart/error/syntactic_errors.dart
index 18fef4cb1080f9546e80018da3cea0a2f7ff98ca..798e30dac4623aef3b37155769a7e8d5ad444c35 100644
--- a/pkg/analyzer/lib/src/dart/error/syntactic_errors.dart
+++ b/pkg/analyzer/lib/src/dart/error/syntactic_errors.dart
@@ -82,6 +82,11 @@ class ParserErrorCode extends ErrorCode {
       "For-in loops use 'in' rather than a colon.",
       "Try replacing the colon with the keyword 'in'.");
 
+  static const ParserErrorCode CONST_AND_COVARIANT = const ParserErrorCode(
+      'CONST_AND_COVARIANT',
+      "Members can't be declared to be both 'const' and 'covariant'.",
+      "Try removing either the 'const' or 'covariant' keyword.");
+
   static const ParserErrorCode CONST_AND_FINAL = const ParserErrorCode(
       'CONST_AND_FINAL',
       "Members can't be declared to be both 'const' and 'final'.",
@@ -142,6 +147,27 @@ class ParserErrorCode extends ErrorCode {
       "A continue statement in a switch statement must have a label as a target.",
       "Try adding a label associated with one of the case clauses to the continue statement.");
 
+  static const ParserErrorCode COVARIANT_AFTER_VAR = const ParserErrorCode(
+      'COVARIANT_AFTER_VAR',
+      "The modifier 'covariant' should be before the modifier 'var'.",
+      "Try re-ordering the modifiers.");
+
+  static const ParserErrorCode COVARIANT_AND_STATIC = const ParserErrorCode(
+      'COVARIANT_AND_STATIC',
+      "Members can't be declared to be both 'covariant' and 'static'.",
+      "Try removing either the 'covariant' or 'static' keyword.");
+
+  static const ParserErrorCode COVARIANT_TOP_LEVEL_DECLARATION =
+      const ParserErrorCode(
+          'COVARIANT_TOP_LEVEL_DECLARATION',
+          "Top-level declarations can't be declared to be covariant.",
+          "Try removing the keyword 'covariant'.");
+
+  static const ParserErrorCode COVARIANT_CONSTRUCTOR = const ParserErrorCode(
+      'COVARIANT_CONSTRUCTOR',
+      "A constructor can't be declared to be 'covariant'.",
+      "Try removing the keyword 'covariant'.");
+
   static const ParserErrorCode DEFAULT_VALUE_IN_FUNCTION_TYPE =
       const ParserErrorCode(
           'DEFAULT_VALUE_IN_FUNCTION_TYPE',
@@ -322,6 +348,11 @@ class ParserErrorCode extends ErrorCode {
           "Field formal parameters can only be used in a constructor.",
           "Try replacing the field formal parameter with a normal parameter.");
 
+  static const ParserErrorCode FINAL_AND_COVARIANT = const ParserErrorCode(
+      'FINAL_AND_COVARIANT',
+      "Members can't be declared to be both 'final' and 'covariant'.",
+      "Try removing either the 'final' or 'covariant' keyword.");
+
   static const ParserErrorCode FINAL_AND_VAR = const ParserErrorCode(
       'FINAL_AND_VAR',
       "Members can't be declared to be both 'final' and 'var'.",