Remove layout tests that run execCommand on non-HTML documents

LayoutTests/svg/custom/layout-loop.svg

Index: LayoutTests/svg/custom/layout-loop.svg
diff --git a/LayoutTests/svg/custom/layout-loop.svg b/LayoutTests/svg/custom/layout-loop.svg
deleted file mode 100644
index 21f6cd229a24414e35ffff65477d4bf17b7c64cf..0000000000000000000000000000000000000000
--- a/LayoutTests/svg/custom/layout-loop.svg
+++ /dev/null
@@ -1,53 +0,0 @@
-<svg xmlns="http://www.w3.org/2000/svg">
-<g>
-    <linearGradient>
-        <stop id="stop"/>
-    </linearGradient>
-</g>
-<g>
-    <defs>
-        <filter id="filter"/>
-    </defs>
-
-    <mask id="mask">
-        <g filter="url(#filter)">
-            <linearGradient id="gradient"/>
-            <path fill="url(#gradient)" d="M147.231,26.23c70.188,0,127.086,57.77,127.086,129.032c0"/>
-        </g>
-    </mask>
-
-    <path mask="url(#mask)" d="M147.231,26.23c70.188,0,127.086,57.77,127.086,129.032"/>
-</g>
-
-<text>PASS, if it doesn't crash.</text>
-<script><![CDATA[
-if (window.testRunner)
-    testRunner.dumpAsText();
-document.execCommand("SelectAll");
-range = document.createRange();
-range.setStartBefore(document.getElementById("stop"));
-range.insertNode(document.getElementById("mask"));
-
-/* What does this do? It moves the whole <mask> element as child of the <linearGradient>.
-The final DOM looks like:
-
-<g>
-    <linearGradient>
-        <mask id="mask">
-            <g filter="url(#filter)">
-                <linearGradient id="gradient"/>
-                <path fill="url(#gradient)" d="..."/>
-            </g>
-        </mask>
-        <stop id="stop"/>
-    </linearGradient>
-</g>
-<g>
-    <defs>
-        <filter id="filter"/>
-    </defs>
-    <path mask="url(#mask)" d="...."/>
-</g>
-*/
-]]></script>
-</svg>