Fix using deprecated analyzer APIs. (#2249)

Author: scheglov

lib/src/model/class.dart

@@ -304,9 +304,8 @@ class Class extends Container
       }
 
       var inheritance = definingLibrary.inheritanceManager;
-      var classType = element.thisType;
-      var cmap = inheritance.getInheritedConcreteMap(classType);
-      var imap = inheritance.getInheritedMap(classType);
+      var cmap = inheritance.getInheritedConcreteMap2(element);
+      var imap = inheritance.getInheritedMap2(element);
 
       var combinedMap = <String, ExecutableElement>{};
       for (var nameObj in cmap.keys) {

lib/src/model/extension.dart

@@ -25,7 +25,7 @@ class Extension extends Container
   bool get alwaysApplies =>
       extendedType.instantiatedType.isDynamic ||
       extendedType.instantiatedType.isVoid ||
-      extendedType.instantiatedType.isObject;
+      extendedType.instantiatedType.isDartCoreObject;
 
   bool couldApplyTo<T extends ExtensionTarget>(T c) =>
       _couldApplyTo(c.modelType);

lib/src/model/getter_setter_combo.dart

@@ -50,7 +50,7 @@ mixin GetterSetterCombo on ModelElement {
     if (constantInitializer is! InstanceCreationExpression) return original;
     var creationExpression = constantInitializer as InstanceCreationExpression;
     var constructorName = creationExpression.constructorName.toString();
-    Element staticElement = creationExpression.staticElement;
+    Element staticElement = creationExpression.constructorName.staticElement;
     if (staticElement == null) {
       warn(PackageWarning.missingConstantConstructor, message: constructorName);
       return original;