[CSS Grid Layout] Remove unused variable in test

Inside method updateImplicitGridColumn() of test
fast/css-grid-layout/implicit-position-dynamic-change.html we define a
variable gridItem that is not used. This patch removes it.

Review URL: https://codereview.chromium.org/213423009

git-svn-id: svn://svn.chromium.org/blink/trunk@170301 bbb929c8-8fbe-4397-9dbb-9b2b20218538

third_party/WebKit/LayoutTests/fast/css-grid-layout/implicit-position-dynamic-change.html

@@ -21,7 +21,6 @@ function testPosition(gridElementID, position, size)
 
 function updateImplicitGridColumn()
 {
-    var gridItem = document.getElementById("constrainedGrid").firstChild;
     testPosition("constrainedGrid", { 'column': '1', 'row': '1' }, { 'width': '50', 'height': '70' });
     testPosition("constrainedGrid", { 'column': '1', 'row': '2' }, { 'width': '50', 'height': '30' });
     testPosition("constrainedGrid", { 'column': '1', 'row': '3' }, { 'width': '50', 'height': '50' });
@@ -48,7 +47,6 @@ function updateImplicitGridColumn()
 
     testPosition("constrainedGrid", { 'column': '10', 'row': '15' }, { 'width': '40', 'height': '30' });
 
-    var gridItem = document.getElementById("constrainedGridUndefinedHeight").firstChild;
     testPosition("constrainedGridUndefinedHeight", { 'column': '1', 'row': '1' }, { 'width': '50', 'height': '70' });
     testPosition("constrainedGridUndefinedHeight", { 'column': '1', 'row': '2' }, { 'width': '50', 'height': '70' });
     testPosition("constrainedGridUndefinedHeight", { 'column': '1', 'row': '3' }, { 'width': '50', 'height': '50' });
@@ -75,7 +73,6 @@ function updateImplicitGridColumn()
 
     testPosition("constrainedGridUndefinedHeight", { 'column': '10', 'row': '15' }, { 'width': '40', 'height': '30' });
 
-    gridItem = document.getElementById("unconstrainedGrid").firstChild;
     testPosition("unconstrainedGrid", { 'column': '1', 'row': '1' }, { 'width': '50', 'height': '70' });
     testPosition("unconstrainedGrid", { 'column': '2', 'row': '1' }, { 'width': '60', 'height': '70' });
     testPosition("unconstrainedGrid", { 'column': '3', 'row': '1' }, { 'width': '130', 'height': '70' });