Make analyzer strong-mode clean

pkg/analyzer/lib/src/summary/link.dart

Index: pkg/analyzer/lib/src/summary/link.dart
diff --git a/pkg/analyzer/lib/src/summary/link.dart b/pkg/analyzer/lib/src/summary/link.dart
index 08cbde181d5bd52df3da15e0f71303a908316d46..f76bdc2b585d6f4d9de1d050a04e57368248c5ac 100644
--- a/pkg/analyzer/lib/src/summary/link.dart
+++ b/pkg/analyzer/lib/src/summary/link.dart
@@ -347,7 +347,7 @@ abstract class ClassElementForLink extends Object
   @override
   final CompilationUnitElementForLink enclosingElement;
 
-  @override
+  /// TODO(brianwilkerson) This appears to be unused and might be removable.
   bool hasBeenInferred;
 
   ClassElementForLink(CompilationUnitElementForLink enclosingElement)
@@ -368,7 +368,7 @@ abstract class ClassElementForLink extends Object
   List<ConstructorElementForLink> get constructors;
 
   @override
-  CompilationUnitElementForLink get enclosingUnit => enclosingElement;
+  CompilationUnitElementImpl get enclosingUnit => enclosingElement;
 
   @override
   List<FieldElementForLink> get fields;
@@ -571,7 +571,7 @@ class ClassElementForLink_Class extends ClassElementForLink
   }
 
   @override
-  DartType get type =>
+  InterfaceType get type =>
       _type ??= buildType((int i) => typeParameterTypes[i], null);
 
   @override
@@ -740,7 +740,7 @@ class ClassElementForLink_Enum extends ClassElementForLink
   InterfaceType get supertype => library._linker.typeProvider.objectType;
 
   @override
-  DartType get type => _type ??= new InterfaceTypeImpl(this);
+  InterfaceType get type => _type ??= new InterfaceTypeImpl(this);
 
   @override
   List<TypeParameterElement> get typeParameters => const [];
@@ -1198,7 +1198,7 @@ class CompilationUnitElementInBuildUnit extends CompilationUnitElementForLink {
               enclosingClass != null ? addReference(enclosingClass) : null,
           dependency: enclosingClass != null
               ? null
-              : library.addDependency(element.library),
+              : library.addDependency(element.library as LibraryElementForLink),
           kind: kind);
     } else if (element is FunctionElementForLink_Initializer) {
       return addRawReference('',
@@ -1629,6 +1629,9 @@ class ConstructorElementForLink extends ExecutableElementForLink_NonLocal
   ConstructorElementForLink get asConstructor => this;
 
   @override
+  ClassElementImpl get enclosingElement => super.enclosingClass;
+
+  @override
   bool get isCycleFree {
     if (!_constNode.isEvaluated) {
       new ConstDependencyWalker().walk(_constNode);
@@ -1852,7 +1855,6 @@ abstract class ExecutableElementForLink extends Object
   String _name;
   String _displayName;
 
-  @override
   final CompilationUnitElementForLink compilationUnit;
 
   ExecutableElementForLink(this.compilationUnit, this._unlinkedExecutable);
@@ -1929,7 +1931,7 @@ abstract class ExecutableElementForLink extends Object
   bool get isSynthetic => false;
 
   @override
-  LibraryElementForLink get library => enclosingElement.library;
+  LibraryElement get library => enclosingElement.library;
 
   @override
   String get name {
@@ -1975,7 +1977,7 @@ abstract class ExecutableElementForLink extends Object
    */
   DartType _computeDefaultReturnType() {
     if (_unlinkedExecutable.kind == UnlinkedExecutableKind.setter &&
-        library._linker.strongMode) {
+        (library as LibraryElementForLink)._linker.strongMode) {
       // In strong mode, setters without an explicit return type are
       // considered to return `void`.
       return VoidTypeImpl.instance;
@@ -3728,6 +3730,9 @@ class MethodElementForLink extends ExecutableElementForLink_NonLocal
   DartType get asStaticType => type;
 
   @override
+  ClassElementImpl get enclosingElement => super.enclosingClass;
+
+  @override
   String get identifier => name;
 
   @override
@@ -3998,7 +4003,7 @@ class ParameterElementForLink_VariableSetter implements ParameterElementImpl {
  * Mixin used by elements that can have parameters.
  */
 abstract class ParameterParentElementForLink implements Element {
-  List<ParameterElementForLink> _parameters;
+  List<ParameterElement> _parameters;
 
   /**
    * Get the appropriate integer list to store in
@@ -4012,11 +4017,11 @@ abstract class ParameterParentElementForLink implements Element {
   /**
    * Get all the parameters of this element.
    */
-  List<ParameterElementForLink> get parameters {
+  List<ParameterElement> get parameters {
     if (_parameters == null) {
       List<UnlinkedParam> unlinkedParameters = this.unlinkedParameters;
       int numParameters = unlinkedParameters.length;
-      _parameters = new List<ParameterElementForLink>(numParameters);
+      _parameters = new List<ParameterElement>(numParameters);
       for (int i = 0; i < numParameters; i++) {
         UnlinkedParam unlinkedParam = unlinkedParameters[i];
         _parameters[i] = new ParameterElementForLink(
@@ -4142,7 +4147,7 @@ class PropertyAccessorElementForLink_Executable
     with ReferenceableElementForLink
     implements PropertyAccessorElementForLink {
   @override
-  SyntheticVariableElementForLink variable;
+  PropertyInducingElement variable;
 
   PropertyAccessorElementForLink_Executable(
       CompilationUnitElementForLink enclosingUnit,
@@ -4175,7 +4180,8 @@ class PropertyAccessorElementForLink_Executable
 
   @override
   ReferenceableElementForLink getContainedName(String name) {
-    return new NonstaticMemberElementForLink(library, this, name);
+    return new NonstaticMemberElementForLink(
+        library as LibraryElementForLink, this, name);
   }
 
   @override