Issue 25504. Fix for ignoring expression bodies in incremental resolver.

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

Index: pkg/analyzer/lib/src/generated/incremental_resolver.dart
diff --git a/pkg/analyzer/lib/src/generated/incremental_resolver.dart b/pkg/analyzer/lib/src/generated/incremental_resolver.dart
index 7d6bb4c7ec97d67880a1633394ba2c19fe309f13..90444a167a7f6491e499f71a06c2a0e93dbd67a6 100644
--- a/pkg/analyzer/lib/src/generated/incremental_resolver.dart
+++ b/pkg/analyzer/lib/src/generated/incremental_resolver.dart
@@ -1493,12 +1493,16 @@ class PoorMansIncrementalResolver {
                 found = true;
               }
             }
-            if (oldParent is BlockFunctionBody &&
-                newParent is BlockFunctionBody) {
-              oldNode = oldParent;
-              newNode = newParent;
-              found = true;
-              break;
+            if (oldParent is FunctionBody || newParent is FunctionBody) {
+              if (oldParent is BlockFunctionBody &&
+                  newParent is BlockFunctionBody) {
+                oldNode = oldParent;
+                newNode = newParent;
+                found = true;
+                break;
+              }
+              logger.log('Failure: not a block function body.');
+              return false;
             }
           }
           if (!found) {