Revert of Allow image documents in MHT if there is only one resource.

third_party/WebKit/LayoutTests/mhtml/image_document.mht

Index: third_party/WebKit/LayoutTests/mhtml/image_document.mht
diff --git a/third_party/WebKit/LayoutTests/mhtml/image_document.mht b/third_party/WebKit/LayoutTests/mhtml/image_document.mht
deleted file mode 100644
index 6c97fb5961dd0f6985fcd2815a499440b02837ec..0000000000000000000000000000000000000000
--- a/third_party/WebKit/LayoutTests/mhtml/image_document.mht
+++ /dev/null
@@ -1,19 +0,0 @@
-From: <Saved by Blink>
-Subject: 128x128_png.png (128?128)
-Date: Fri, 13 Oct 2016 17:40:08 -0000
-MIME-Version: 1.0
-Content-Type: multipart/related;
-	type="text/html";
-	boundary="----MultipartBoundary--Xm93PP2BFJf8elJGRutH4cfnMaBMcK4sxf4o3u4L2F----"
-
-------MultipartBoundary--Xm93PP2BFJf8elJGRutH4cfnMaBMcK4sxf4o3u4L2F----
-Content-Type: image/png
-Content-Transfer-Encoding: base64
-Content-Location: http://localhost/resources/red_square.png
-
-iVBORw0KGgoAAAANSUhEUgAAAB4AAAAeCAYAAAA7MK6iAAAAAXNSR0IArs4c6QAAAARnQU1BAACx
-jwv8YQUAAAAJcEhZcwAADsQAAA7EAZUrDhsAAACESURBVEhL7ZYxDoAwCEXB2LGTo46ewXj/zXgV
-PQKgexP/Ai6l889/6Stp4HtZjYKOiRCpEpfSEIYgJqxNMFTkFUjVXiZhT6qGirwCqdrLJOxJ1VCR
-V6A/1XxNc9jqQ6JkpjTU2rwQR+5c4769YCM5zn/BX4PY33Dljb0+JtiTqqEir8ADWEIY6dz7d1cA
-AAAASUVORK5CYII=
-------MultipartBoundary--Xm93PP2BFJf8elJGRutH4cfnMaBMcK4sxf4o3u4L2F------