Remove side effects from toString method

- toString method should not have side effect, otherwise it could
be difficult to understand some behavior during debug sesssion
since content of object can change due to the calls to toString
done by the debugger.

Change-Id: I50736ea779f3afeb3903c8110a33500bfe3bd0b3
diff --git a/src/main/java/com/android/tools/r8/ir/code/IRCode.java b/src/main/java/com/android/tools/r8/ir/code/IRCode.java
index 9c0a66b..20bba3f 100644
--- a/src/main/java/com/android/tools/r8/ir/code/IRCode.java
+++ b/src/main/java/com/android/tools/r8/ir/code/IRCode.java
@@ -89,7 +89,6 @@
 
   @Override
   public String toString() {
-    ensureBlockNumbering();
     StringBuilder builder = new StringBuilder();
     builder.append("blocks:\n");
     for (BasicBlock block : blocks) {