Remove unnecessary keep for the default method in Assumer.

Test: tools/test.py *interfaces*

Bug: 143590191
Change-Id: Id1bd42ca1cc08bc81009b7e0d542309d0a9097dc
diff --git a/src/main/java/com/android/tools/r8/ir/optimize/Assumer.java b/src/main/java/com/android/tools/r8/ir/optimize/Assumer.java
index dfabec5..334a606 100644
--- a/src/main/java/com/android/tools/r8/ir/optimize/Assumer.java
+++ b/src/main/java/com/android/tools/r8/ir/optimize/Assumer.java
@@ -3,7 +3,6 @@
 // BSD-style license that can be found in the LICENSE file.
 package com.android.tools.r8.ir.optimize;
 
-import com.android.tools.r8.Keep;
 import com.android.tools.r8.ir.code.Assume;
 import com.android.tools.r8.ir.code.BasicBlock;
 import com.android.tools.r8.ir.code.IRCode;
@@ -14,9 +13,6 @@
 /**
  * One that assumes. Inherited tracker/optimization insert necessary variants of {@link Assume}.
  */
-// TODO(b/143590191): should not need an explicit keep annotation to prevent the default interface
-//  method from being shrunk.
-@Keep
 public interface Assumer {
   default void insertAssumeInstructions(IRCode code) {
     insertAssumeInstructionsInBlocks(code, code.listIterator(), Predicates.alwaysTrue());