[dart2js] Disable assignment chaining optimization

Disable while we look into variable allocator assertion.

Change-Id: Ib1e7c2eb869020ae8ecfa123801009adb6a742c7
Reviewed-on: https://dart-review.googlesource.com/c/93925
Reviewed-by: Sigmund Cherem <sigmund@google.com>
Commit-Queue: Stephen Adams <sra@google.com>
diff --git a/pkg/compiler/lib/src/ssa/codegen.dart b/pkg/compiler/lib/src/ssa/codegen.dart
index 7efacf8..1252521 100644
--- a/pkg/compiler/lib/src/ssa/codegen.dart
+++ b/pkg/compiler/lib/src/ssa/codegen.dart
@@ -356,7 +356,8 @@
         .visitGraph(graph);
     new SsaTypeKnownRemover().visitGraph(graph);
     new SsaTrustedCheckRemover(_options).visitGraph(graph);
-    new SsaAssignmentChaining(_options, _closedWorld).visitGraph(graph);
+    // TODO(sra): Re-enable chaining.
+    //     new SsaAssignmentChaining(_options, _closedWorld).visitGraph(graph);
     new SsaInstructionMerger(
             _abstractValueDomain, generateAtUseSite, _superMemberData)
         .visitGraph(graph);
diff --git a/tests/compiler/dart2js/codegen/load_elimination_test.dart b/tests/compiler/dart2js/codegen/load_elimination_test.dart
index ed5d04c..822a582 100644
--- a/tests/compiler/dart2js/codegen/load_elimination_test.dart
+++ b/tests/compiler/dart2js/codegen/load_elimination_test.dart
@@ -262,7 +262,8 @@
     await test(TEST_14, 'return t1[0]');
     await test(TEST_15, 'return 42');
     await test(TEST_16, 'return \$.a');
-    await test(TEST_17, r'return $.x === 0 ? $.a = true : $.a = false');
+    await test(TEST_17,
+        RegExp(r'return (t1|\$\.x === 0 \? \$\.a = true : \$\.a = false);'));
     await test(TEST_18, 'return t1');
   }