Remove unneeded assert bailout.

Bug: 150736225
Change-Id: I2489ee52b06124f9af991a4341ce65484d30ec94
diff --git a/src/main/java/com/android/tools/r8/shaking/AppInfoWithLiveness.java b/src/main/java/com/android/tools/r8/shaking/AppInfoWithLiveness.java
index a88d372..78b47e4 100644
--- a/src/main/java/com/android/tools/r8/shaking/AppInfoWithLiveness.java
+++ b/src/main/java/com/android/tools/r8/shaking/AppInfoWithLiveness.java
@@ -518,21 +518,10 @@
     return new AppInfoWithLivenessModifier();
   }
 
-  private boolean assertDefinitionFor = true;
-
-  public void disableDefinitionForAssert() {
-    assertDefinitionFor = false;
-  }
-
-  public void enableDefinitionForAssert() {
-    assertDefinitionFor = true;
-  }
-
   @Override
   public DexClass definitionFor(DexType type) {
     DexClass definition = super.definitionFor(type);
-    assert !assertDefinitionFor
-            || definition != null
+    assert definition != null
             || deadProtoTypes.contains(type)
             || missingTypes.contains(type)
             // TODO(b/150693139): Remove these exceptions once fixed.