Prepare CompilationUnitElementDelta in IncrementalCompilationUnitElementBuilder.

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

Index: pkg/analyzer/lib/src/generated/ast.dart
diff --git a/pkg/analyzer/lib/src/generated/ast.dart b/pkg/analyzer/lib/src/generated/ast.dart
index 3a2822f02b3ef02c6a5d1ac6dc23cc0ecaebcf18..61a3251440a26c36d9a0e22f169c560d9a146e39 100644
--- a/pkg/analyzer/lib/src/generated/ast.dart
+++ b/pkg/analyzer/lib/src/generated/ast.dart
@@ -4775,6 +4775,18 @@ class CompilationUnit extends AstNode {
     return lastDirective.offset < firstDeclaration.offset;
   }
 
+  /**
+   * Replaces contents of this [CompilationUnit] with the given [other].
+   */
+  void replaceWith(CompilationUnit other) {

[Brian Wilkerson, 2015/06/02 15:50:41]

I really don't think we want to add this to the public API, and certainly not
with the current semantics that the parent of the child nodes doesn't change.

Is that an important semantic to preserve? If not, perhaps this could be moved
to Incremental...Builder and the setters invoked to preserve the parent/child
relationships.

[scheglov, 2015/06/02 17:13:11]

Oops... You're right.
Removing it.

+    beginToken = other.beginToken;
+    _scriptTag = other._scriptTag;
+    _directives = other._directives;
+    _declarations = other._declarations;
+    element = other.element;
+    lineInfo = other.lineInfo;
+  }
+
   @override
   accept(AstVisitor visitor) => visitor.visitCompilationUnit(this);