Make catch variables final.

pkg/front_end/lib/src/fasta/kernel/body_builder.dart

 // Copyright (c) 2016, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library fasta.body_builder;
 
 import '../parser/parser.dart' show FormalParameterType, optional;
 
 import '../parser/error_kind.dart' show ErrorKind;
 
@@ skipping 1375 matching lines @@
     int charOffset = thisKeyword?.charOffset;
     if (thisKeyword != null) {
       if (!inConstructor) {
         addCompileTimeError(thisKeyword.charOffset,
             "'this' parameters can only be used on constructors.");
         thisKeyword = null;
       }
     }
     Identifier name = pop();
     DartType type = pop();
-    pop(); // Modifiers.
+    int modifiers = Modifier.validate(pop());
+    if (inCatchClause) {
+      modifiers |= finalMask;
+    }
+    bool isConst = (modifiers & constMask) != 0;
+    bool isFinal = (modifiers & finalMask) != 0;
     ignore(Unhandled.Metadata);
     VariableDeclaration variable;
     if (!inCatchClause && functionNestingLevel == 0) {
       dynamic builder = formalParameterScope.lookup(name.name, charOffset, uri);
       if (builder == null) {
         if (thisKeyword == null) {
           internalError("Internal error: formal missing for '${name.name}'");
         } else {
           addCompileTimeError(thisKeyword.charOffset,
               "'${name.name}' isn't a field in this class.");
           thisKeyword = null;
         }
       } else if (thisKeyword == null) {
         variable = builder.build(library);
         variable.initializer = name.initializer;
       } else if (builder.isField && builder.parent == classBuilder) {
         FieldBuilder field = builder;
         if (type != null) {
           nit("Ignoring type on 'this' parameter '${name.name}'.",
               thisKeyword.charOffset);
         }
         type = field.target.type ?? const DynamicType();
         variable = new VariableDeclaration(name.name,
-            type: type, initializer: name.initializer);
+            type: type,
+            initializer: name.initializer,
+            isFinal: isFinal,
+            isConst: isConst)..fileOffset = name.fileOffset;
       } else {
         addCompileTimeError(
             name.fileOffset, "'${name.name}' isn't a field in this class.");
       }
     }
     variable ??= new VariableDeclaration(name.name,
         type: type ?? const DynamicType(),
-        initializer: name.initializer)..fileOffset = name.fileOffset;
+        initializer: name.initializer,
+        isFinal: isFinal,
+        isConst: isConst)..fileOffset = name.fileOffset;
     push(variable);
   }
 
   @override
   void endOptionalFormalParameters(
       int count, Token beginToken, Token endToken) {
     debugEvent("OptionalFormalParameters");
     FormalParameterType kind = optional("{", beginToken)
         ? FormalParameterType.NAMED
         : FormalParameterType.POSITIONAL;
@@ skipping 1447 matching lines @@
   } else if (node is PrefixBuilder) {
     return node.name;
   } else if (node is ThisAccessor) {
     return node.isSuper ? "super" : "this";
   } else if (node is BuilderAccessor) {
     return node.plainNameForRead;
   } else {
     return internalError("Unhandled: ${node.runtimeType}");
   }
 }