Fix Google3 specific flag

Change-Id: Ia77d4d68f7052e7d5d92c8114b277f9b2ecb2e87
diff --git a/src/main/java/com/android/tools/r8/R8Command.java b/src/main/java/com/android/tools/r8/R8Command.java
index cef341c..ec7209a 100644
--- a/src/main/java/com/android/tools/r8/R8Command.java
+++ b/src/main/java/com/android/tools/r8/R8Command.java
@@ -1054,7 +1054,7 @@
         synthesizedClassPrefix.isEmpty()
             ? System.getProperty("com.android.tools.r8.synthesizedClassPrefix", "")
             : synthesizedClassPrefix;
-    boolean l8Shrinking = !synthesizedClassPrefix.isEmpty();
+    boolean l8Shrinking = !internal.synthesizedClassPrefix.isEmpty();
     // TODO(b/214382176): Enable all the time.
     internal.loadAllClassDefinitions = l8Shrinking;
     if (l8Shrinking) {