Fix webkit tests failing on the bots

webkit/support/platform_support_mac.mm

Index: webkit/support/platform_support_mac.mm
===================================================================
--- webkit/support/platform_support_mac.mm	(revision 175576)
+++ webkit/support/platform_support_mac.mm	(working copy)
@@ -226,6 +226,7 @@
       // use a PNG. The GIF doesn't have the color range needed to correctly
       // match the TIFF they use in Safari.
       path = path.AppendASCII("missingImage.png");
+      file_util::AbsolutePath(&path);
       bool success = file_util::ReadFileToString(path, &broken_image_data);
       if (!success) {
         LOG(FATAL) << "Failed reading: " << path.value();
@@ -239,6 +240,7 @@
     if (resize_corner_data.empty()) {
       FilePath path = GetResourcesFilePath();
       path = path.AppendASCII("textAreaResizeCorner.png");
+      file_util::AbsolutePath(&path);
       bool success = file_util::ReadFileToString(path, &resize_corner_data);
       if (!success) {
         LOG(FATAL) << "Failed reading: " << path.value();