Address review comments in outliner

Change-Id: I731a2ce2d481c7a42e7c4ebfe8948ab4f644f92e
diff --git a/src/main/java/com/android/tools/r8/ir/optimize/outliner/bottomup/OutlineMarkerRewriter.java b/src/main/java/com/android/tools/r8/ir/optimize/outliner/bottomup/OutlineMarkerRewriter.java
index 539b38d..38ecd97 100644
--- a/src/main/java/com/android/tools/r8/ir/optimize/outliner/bottomup/OutlineMarkerRewriter.java
+++ b/src/main/java/com/android/tools/r8/ir/optimize/outliner/bottomup/OutlineMarkerRewriter.java
@@ -236,7 +236,8 @@
   // In debug mode the out-value of outlined calls to StringBuilder#append may be used outside the
   // outline. In this case we replace the out-value by the receiver of the call.
   //
-  // In release mode calls to StringBuilder#append does not have an out-value.
+  // In release mode calls to StringBuilder#append does not have an out-value, since our "returns
+  // receiver" modeling replaces all uses of the out-value by the receiver.
   private void fixupOutlinedOutValue(Instruction outlinedInstruction) {
     if (outlinedInstruction.hasOutValue()
         && outlinedInstruction.outValue().hasNonDebugUsers()