assign to null to clear a local variable, avoid delete

1 files changed, 2 insertions, 2 deletions

diff --git a/tools/js-optimizer.js b/tools/js-optimizer.js
index 5fd0f138..b35da99d 100644
--- a/tools/js-optimizer.js
+++ b/tools/js-optimizer.js
@@ -2670,8 +2670,8 @@ function registerizeHarder(ast) {
         junctions[block.exit].inblocks[block.id] = 1;
       }
     }
-    delete labelledBlocks;
-    delete labelledJumps;
+    labelledBlocks = null;
+    labelledJumps = null;
 
     // Do a backwards data-flow analysis to determine the set of live
     // variables at each junction, and to use this information to eliminate