Cache ElementLocation instance and index key/location ids.

pkg/analyzer/lib/src/generated/element.dart

Index: pkg/analyzer/lib/src/generated/element.dart
diff --git a/pkg/analyzer/lib/src/generated/element.dart b/pkg/analyzer/lib/src/generated/element.dart
index a1fc144dbf098860bb539023d658610914e67a6a..937f1d042eb83fab3cc6c98553c89a54f7feba34 100644
--- a/pkg/analyzer/lib/src/generated/element.dart
+++ b/pkg/analyzer/lib/src/generated/element.dart
@@ -3454,6 +3454,11 @@ abstract class ElementImpl implements Element {
   int _cachedHashCode = 0;
 
   /**
+   * A cached copy of the calculated location for this element.
+   */
+  ElementLocation _cachedLocation;
+
+  /**
    * Initialize a newly created element to have the given name.
    *
    * @param name the name of this element
@@ -3559,7 +3564,12 @@ abstract class ElementImpl implements Element {
       getAncestor((element) => element is LibraryElement);
 
   @override
-  ElementLocation get location => new ElementLocationImpl.con1(this);
+  ElementLocation get location {
+    if (_cachedLocation == null) {
+      _cachedLocation = new ElementLocationImpl.con1(this);
+    }
+    return _cachedLocation;
+  }
 
   @override
   String get name => _name;
@@ -3949,6 +3959,21 @@ class ElementLocationImpl implements ElementLocation {
   List<String> _components;
 
   /**
+   * The object managing [indexKeyId] and [indexLocationId].
+   */
+  Object indexOwner;
+
+  /**
+   * A cached id of this location in index.
+   */
+  int indexKeyId;
+
+  /**
+   * A cached id of this location in index.
+   */
+  int indexLocationId;
+
+  /**
    * Initialize a newly created location to represent the given element.
    *
    * @param element the element whose location is being represented