[pkg/vm_snapshot_analysis] Don't assume Code objects have an owner.

For regular stubs, the owner will be null.

Issue: https://github.com/flutter/flutter/issues/130009
Change-Id: I8c85e3130128af79c596f381869d61631221cf9e
Cq-Include-Trybots: luci.dart.try:pkg-mac-release-try,pkg-mac-release-arm64-try,pkg-linux-release-try
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/312660
Reviewed-by: Slava Egorov <vegorov@google.com>
Commit-Queue: Tess Strickland <sstrickl@google.com>

pkg/vm_snapshot_analysis/CHANGELOG.md

@@ -1,5 +1,10 @@
 # Changelog
 
+## 0.7.5
+
+- Fix for flutter/flutter#130009 where an attempt to lookup the owner info
+node for type testing stubs would cause a null check error.
+
 ## 0.7.4
 
 - Fix for flutter/flutter#128402 where an attempt to lookup the owner info

pkg/vm_snapshot_analysis/lib/v8_profile.dart

@@ -413,16 +413,16 @@ class _ProgramInfoBuilder {
   ProgramInfoNode? createInfoNodeFor(Node node) {
     switch (node.type) {
       case 'Code':
-        final owner = node['owner_']!;
-        if (owner.type == 'Function') {
+        final owner = node['owner_']; // Stubs may have no owner.
+        if (owner?.type == 'Function') {
           // For normal functions we just attribute Code object and all
           // objects dominated by it to the function itself.
-          return getInfoNodeFor(owner)!;
+          return getInfoNodeFor(owner!)!;
         }
         // For all stub types, we create a dummy functionNode that is going to
         // own all objects dominated by it.
         final ownerNode =
-            owner.type == 'Class' ? getInfoNodeFor(owner)! : program.stubs;
+            owner?.type == 'Class' ? getInfoNodeFor(owner!)! : program.stubs;
         return makeInfoNode(node.index,
             name: node.name, parent: ownerNode, type: NodeType.functionNode);
 

pkg/vm_snapshot_analysis/pubspec.yaml

@@ -1,5 +1,5 @@
 name: vm_snapshot_analysis
-version: 0.7.4
+version: 0.7.5
 description: Utilities for analysing AOT snapshot size.
 repository: https://github.com/dart-lang/sdk/tree/main/pkg/vm_snapshot_analysis