Setup correct scope for initializers and complain about fields initialized more than once.

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

Index: pkg/front_end/lib/src/fasta/kernel/fasta_accessors.dart
diff --git a/pkg/front_end/lib/src/fasta/kernel/fasta_accessors.dart b/pkg/front_end/lib/src/fasta/kernel/fasta_accessors.dart
index 4ab29f91e69b9370f2b6842a017b182944c93363..f5b921fc2b7d14f4ef2351379d58d0e28ec3fd53 100644
--- a/pkg/front_end/lib/src/fasta/kernel/fasta_accessors.dart
+++ b/pkg/front_end/lib/src/fasta/kernel/fasta_accessors.dart
@@ -73,7 +73,10 @@ abstract class BuilderHelper {
 
   Expression buildCompileTimeError(error, [int offset]);
 
-  Initializer buildInvalidIntializer(Expression expression, [int offset]);
+  Initializer buildInvalidInitializer(Expression expression, [int offset]);
+
+  Initializer buildFieldInitializer(
+      String name, int offset, Expression expression);
 
   Initializer buildSuperInitializer(
       Constructor constructor, Arguments arguments,
@@ -123,10 +126,9 @@ abstract class FastaAccessor implements Accessor {
 
   Expression buildForEffect() => buildSimpleRead();
 
-  Initializer buildFieldInitializer(
-      Map<String, FieldInitializer> initializers) {
+  Initializer buildFieldInitializer(Map<String, int> initializedFields) {
     int offset = offsetForToken(token);
-    return helper.buildInvalidIntializer(
+    return helper.buildInvalidInitializer(
         helper.buildCompileTimeError(
             // TODO(ahe): This error message is really bad.
             "Can't use $plainNameForRead here.",
@@ -192,9 +194,8 @@ abstract class ErrorAccessor implements FastaAccessor {
   withReceiver(Object receiver, int operatorOffset, {bool isNullAware}) => this;
 
   @override
-  Initializer buildFieldInitializer(
-      Map<String, FieldInitializer> initializers) {
-    return helper.buildInvalidIntializer(
+  Initializer buildFieldInitializer(Map<String, int> initializedFields) {
+    return helper.buildInvalidInitializer(
         buildError(new Arguments.empty(), isSetter: true));
   }
 
@@ -293,11 +294,11 @@ class ThisAccessor extends FastaAccessor {
     }
   }
 
-  Initializer buildFieldInitializer(
-      Map<String, FieldInitializer> initializers) {
+  @override
+  Initializer buildFieldInitializer(Map<String, int> initializedFields) {
     String keyword = isSuper ? "super" : "this";
     int offset = offsetForToken(token);
-    return helper.buildInvalidIntializer(
+    return helper.buildInvalidInitializer(
         helper.buildCompileTimeError(
             "Can't use '$keyword' here, did you mean '$keyword()'?", offset),
         offset);
@@ -346,7 +347,7 @@ class ThisAccessor extends FastaAccessor {
     if (constructor == null ||
         !helper.checkArguments(
             constructor.function, arguments, <TypeParameter>[])) {
-      return helper.buildInvalidIntializer(
+      return helper.buildInvalidInitializer(
           buildThrowNoSuchMethodError(arguments,
               isSuper: isSuper, name: name.name, offset: offset),
           offset);
@@ -779,6 +780,12 @@ class NullAwarePropertyAccessor extends kernel.NullAwarePropertyAccessor
   toString() => "NullAwarePropertyAccessor()";
 }
 
+int adjustForImplicitCall(String name, int offset) {
+  // Normally the offset is at the start of the token, but in this case,
+  // because we insert a '.call', we want it at the end instead.
+  return offset + (name?.length ?? 0);
+}
+
 class VariableAccessor extends kernel.VariableAccessor with FastaAccessor {
   VariableAccessor(
       BuilderHelper helper, Token token, VariableDeclaration variable,
@@ -788,10 +795,8 @@ class VariableAccessor extends kernel.VariableAccessor with FastaAccessor {
   String get plainNameForRead => variable.name;
 
   Expression doInvocation(int offset, Arguments arguments) {
-    // Normally the offset is at the start of the token, but in this case,
-    // because we insert a '.call', we want it at the end instead.
     return helper.buildMethodInvocation(buildSimpleRead(), callName, arguments,
-        offset + (variable.name?.length ?? 0));
+        adjustForImplicitCall(plainNameForRead, offset));
   }
 
   toString() => "VariableAccessor()";
@@ -805,15 +810,15 @@ class ReadOnlyAccessor extends kernel.ReadOnlyAccessor with FastaAccessor {
       : super(helper, expression, token);
 
   Expression doInvocation(int offset, Arguments arguments) {
-    return helper.buildMethodInvocation(
-        buildSimpleRead(), callName, arguments, offset);
+    return helper.buildMethodInvocation(buildSimpleRead(), callName, arguments,
+        adjustForImplicitCall(plainNameForRead, offset));
   }
 }
 
 class ParenthesizedExpression extends ReadOnlyAccessor {
   ParenthesizedExpression(
       BuilderHelper helper, Expression expression, Token token)
-      : super(helper, expression, "<a parenthesized expression>", token);
+      : super(helper, expression, null, token);
 
   Expression makeInvalidWrite(Expression value) {
     return helper.buildCompileTimeError(