tests: fix failures introduced in 7359cb753a54

tests/test-hgweb-commands.t

@@ -807,7 +807,7 b' Overviews'
   
   <div id="wrapper">
   <ul id="nodebgs"></ul>
-  <canvas id="graph" width="224" height="129"></canvas>
+  <canvas id="graph" width="480" height="129"></canvas>
   <ul id="graphnodes"></ul>
   </div>
   

tests/test-hgweb-empty.t

@@ -232,7 +232,7 b' Some tests for hgweb in an empty reposit'
   
   <div id="wrapper">
   <ul id="nodebgs"></ul>
-  <canvas id="graph" width="224" height="12"></canvas>
+  <canvas id="graph" width="480" height="12"></canvas>
   <ul id="graphnodes"></ul>
   </div>