Fix assertion failure from unexpected abstract value

Change-Id: I0610cd56f54bea5eeb0e286e8d5922314ee95b7e
diff --git a/src/main/java/com/android/tools/r8/ir/analysis/fieldaccess/FieldAssignmentTracker.java b/src/main/java/com/android/tools/r8/ir/analysis/fieldaccess/FieldAssignmentTracker.java
index 2b63089..ccef272 100644
--- a/src/main/java/com/android/tools/r8/ir/analysis/fieldaccess/FieldAssignmentTracker.java
+++ b/src/main/java/com/android/tools/r8/ir/analysis/fieldaccess/FieldAssignmentTracker.java
@@ -223,11 +223,6 @@
                 >= initialAbstractValue.getAbstractionSize()) {
               abstractValue = UnknownValue.getInstance();
             }
-          } else {
-            assert false
-                : "Expected abstract value of "
-                    + field.toSourceString()
-                    + " to be instance of NonConstantNumberValue";
           }
         }