Modifies few gc related layout tests to work with ignition.

third_party/WebKit/LayoutTests/fast/xpath/xpath-snapshot-result-should-mark-its-nodeset.html

Index: third_party/WebKit/LayoutTests/fast/xpath/xpath-snapshot-result-should-mark-its-nodeset.html
diff --git a/third_party/WebKit/LayoutTests/fast/xpath/xpath-snapshot-result-should-mark-its-nodeset.html b/third_party/WebKit/LayoutTests/fast/xpath/xpath-snapshot-result-should-mark-its-nodeset.html
index aae0b63bbc6978383f87ee1f922651ab47ceb6a1..36398c81323d2d2ddbb354bd8417eb4af4c1ea18 100644
--- a/third_party/WebKit/LayoutTests/fast/xpath/xpath-snapshot-result-should-mark-its-nodeset.html
+++ b/third_party/WebKit/LayoutTests/fast/xpath/xpath-snapshot-result-should-mark-its-nodeset.html
@@ -18,9 +18,16 @@
 
         function test(type)
         {
-            var result = document.evaluate("//div", document.documentElement, null, type, null);
-            result.snapshotItem(0).foo = "PASS";
-            document.body.removeChild(result.snapshotItem(0));
+            var result;
+            function initialize() {
+                result = document.evaluate("//div", document.documentElement, null, type, null);
+                result.snapshotItem(0).foo = "PASS";
+                document.body.removeChild(result.snapshotItem(0));
+            }
+
+            // Perform all assignments in a function to avoid references to objects
+            // in dead registers when using ignition (chromium:595672)
+            initialize();
             gc();
             var console = document.getElementById("console");
             console.appendChild(document.createTextNode(result.snapshotItem(0).foo));