Remove multiple GC calls and replace GCController.collect calls with GCController.collectAll

LayoutTests/resources/magnitude-perf.js

Index: LayoutTests/resources/magnitude-perf.js
diff --git a/LayoutTests/resources/magnitude-perf.js b/LayoutTests/resources/magnitude-perf.js
index 70d69efd42d1bed5a0dcd58cfacb68b44c5aea9e..7d61b93862d3b67dbdb512feb4c2423b9036e65e 100644
--- a/LayoutTests/resources/magnitude-perf.js
+++ b/LayoutTests/resources/magnitude-perf.js
@@ -199,11 +199,7 @@ Magnitude._runTime = function(setup, test, magnitude)
         if (GCController.getJSObjectCount)
             debugStr += ' jsObjectCountBefore ' + GCController.getJSObjectCount();
 
-        // Do a gc to reduce likelihood of gc during the test run.
-        // Do multiple gc's for V8 to clear DOM wrappers.
-        GCController.collect();
-        GCController.collect();
-        GCController.collect();
+        GCController.collectAll();
 
         if (GCController.getJSObjectCount)
             debugStr += ' jsObjectCountAfter ' + GCController.getJSObjectCount();