Verify AST instead of constant values.

pkg/analyzer/tool/summary/idl.dart

Index: pkg/analyzer/tool/summary/idl.dart
diff --git a/pkg/analyzer/tool/summary/idl.dart b/pkg/analyzer/tool/summary/idl.dart
index 0eb13f6b485fdefec3a45bdffaabed2ab21f22e1..c75c1275b985f758b19bff42d81e01aae1017163 100644
--- a/pkg/analyzer/tool/summary/idl.dart
+++ b/pkg/analyzer/tool/summary/idl.dart
@@ -637,12 +637,16 @@ enum UnlinkedConstOperation {
   /**
    * Pop the top 2 values from the stack, evaluate `v1 == v2`, and push the
    * result back onto the stack.
-   *
-   * This is also used to represent `v1 != v2`, by composition with [not].
    */
   equal,
 
   /**
+   * Pop the top 2 values from the stack, evaluate `v1 != v2`, and push the
+   * result back onto the stack.
+   */
+  notEqual,
+
+  /**
    * Pop the top value from the stack, compute its boolean negation, and push
    * the result back onto the stack.
    */