Remove lazy sweeping.

test/mjsunit/regress/regress-1708.js

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 // Regression test of a very rare corner case where left-trimming an
 // array caused invalid marking bit patterns on lazily swept pages.
+//
+// Lazy sweeping was deprecated. We are keeping the test case to make
+// sure that concurrent sweeping, which relies on similar assumptions
+// as lazy sweeping works correctly.
 
 // Flags: --expose-gc --noincremental-marking --max-new-space-size 1000
 
 (function() {
   var head = new Array(1);
   var tail = head;
 
-  // Fill heap to increase old-space size and trigger lazy sweeping on
+  // Fill heap to increase old-space size and trigger concurrent sweeping on
   // some of the old-space pages.
   for (var i = 0; i < 200; i++) {
     tail[1] = new Array(1000);
     tail = tail[1];
   }
   array = new Array(100);
   gc(); gc();
 
   // At this point "array" should have been promoted to old-space and be
-  // located in a lazy swept page with intact marking bits. Now shift
+  // located in a concurrently swept page with intact marking bits. Now shift
   // the array to trigger left-trimming operations.
   assertEquals(100, array.length);
   for (var i = 0; i < 50; i++) {
     array.shift();
   }
   assertEquals(50, array.length);
 
   // At this point "array" should have been trimmed from the left with
   // marking bits being correctly transfered to the new object start.
-  // Scavenging operations cause lazy sweeping to advance and verify
+  // Scavenging operations cause concurrent sweeping to advance and verify
   // that marking bit patterns are still sane.
   for (var i = 0; i < 200; i++) {
     tail[1] = new Array(1000);
     tail = tail[1];
   }
 })();