Clarify unquickening comment.

Test: test.py
Change-Id: I0445b76d95dbe81f6fb4dbbf49965231ec2f81e4
diff --git a/runtime/dex_to_dex_decompiler.cc b/runtime/dex_to_dex_decompiler.cc
index 3ae3a52..908405b 100644
--- a/runtime/dex_to_dex_decompiler.cc
+++ b/runtime/dex_to_dex_decompiler.cc
@@ -101,8 +101,9 @@
 
       case Instruction::NOP:
         if (quicken_info_number_of_indices_ > 0) {
-          // Only try to decompile NOP if there are more than 0 indices. The 0 index case happens
-          // for tests like 981.
+          // Only try to decompile NOP if there are more than 0 indices. Not having
+          // any index happens when we unquicken a code item that only has
+          // RETURN_VOID_NO_BARRIER as quickened instruction.
           DecompileNop(inst);
         }
         break;