Increment right debugging counter in StringOptimizer

Change-Id: I39fd7a9e627907f9c750393eee3fb5a52d81a638
diff --git a/src/main/java/com/android/tools/r8/ir/optimize/string/StringOptimizer.java b/src/main/java/com/android/tools/r8/ir/optimize/string/StringOptimizer.java
index 7728c1b..2751153 100644
--- a/src/main/java/com/android/tools/r8/ir/optimize/string/StringOptimizer.java
+++ b/src/main/java/com/android/tools/r8/ir/optimize/string/StringOptimizer.java
@@ -205,7 +205,7 @@
                 invoke.getLocalInfo());
         affectedValues.addAll(invoke.outValue().affectedValues());
         it.replaceCurrentInstruction(new ConstString(newOutValue, resultString, throwingInfo));
-        numberOfSimplifiedConversions++;
+        numberOfSimplifiedOperations++;
         continue;
       }