Revert of [turbofan] ChangeFloat64ToTagged shouldn't canonicalize.

src/js/regexp.js

Index: src/js/regexp.js
diff --git a/src/js/regexp.js b/src/js/regexp.js
index b3d28bab50af3f1d33398fde9ef6c98b2334df32..396b694ea65a35a03292a2a0d964690297121397 100644
--- a/src/js/regexp.js
+++ b/src/js/regexp.js
@@ -178,20 +178,11 @@
   var sticky = TO_BOOLEAN(REGEXP_STICKY(this));
   var updateLastIndex = global || sticky;
   if (updateLastIndex) {
-    // TODO(jgruber): This is actually ToLength in the spec, but we bailout
-    // to the runtime in %_RegExpExec if lastIndex is not a Smi, so we are
-    // smart here and trick both TurboFan and Crankshaft to produce a Smi.
-    // This is a terrible hack, and correct for subtle reasons; it's a clear
-    // indicator that we need a predictable RegExp implementation where we
-    // don't need to add specific work-arounds for certain compiler issues.
-    lastIndex = +this.lastIndex;
+    lastIndex = TO_LENGTH(this.lastIndex);
     if (lastIndex > string.length) {
       this.lastIndex = 0;
       return null;
-    } else if (lastIndex <= 0) {
-      lastIndex = 0;
-    }
-    lastIndex = lastIndex|0;
+    }
   } else {
     lastIndex = 0;
   }