Add SVG as a picture supported mime type

LayoutTests/fast/dom/HTMLImageElement/image-picture-1x.html

Index: LayoutTests/fast/dom/HTMLImageElement/image-picture-1x.html
diff --git a/LayoutTests/fast/dom/HTMLImageElement/image-picture-1x.html b/LayoutTests/fast/dom/HTMLImageElement/image-picture-1x.html
index 5c87fdbfb8b8568e9726af6bdc48b553a41b80d1..bb24b384a102abd098fde284c5f9bfb8866c44f5 100644
--- a/LayoutTests/fast/dom/HTMLImageElement/image-picture-1x.html
+++ b/LayoutTests/fast/dom/HTMLImageElement/image-picture-1x.html
@@ -18,6 +18,8 @@
         shouldBe('currentSrcFileName("img_before_source")', '"blue_rect.jpg?1"');
         shouldBe('document.getElementById("unknown_type").clientWidth', '1600');
         shouldBe('currentSrcFileName("unknown_type")', '"image-set-4x.png?3"');
+        shouldBe('document.getElementById("svg_type").clientWidth', '800');
+        shouldBe('currentSrcFileName("svg_type")', '"image-set-2x.png?2"');
         shouldBe('document.getElementById("empty_srcset").clientWidth', '1600');
         shouldBe('currentSrcFileName("empty_srcset")', '"image-set-4x.png?3"');
         shouldBe('document.getElementById("no_srcset").clientWidth', '1600');
@@ -78,6 +80,16 @@
         resources/image-set-4x.png?3 1600w">
     <img id="unknown_type" src="resources/blue_rect.jpg?1">
 </picture>
+<!-- SVG source - should not be ignored -->
+<picture>
+    <source media="(max-width: 400px)" sizes="400px" srcset="../../hidpi/resources/image-set-1x.png?1 400w, ../../hidpi/resources/image-set-2x.png?1 800w,
+        resources/image-set-4x.png?1 1600w">
+    <source media="(max-width: 800px)" type="image/svg+xml" sizes="800px" srcset="../../hidpi/resources/image-set-1x.png?2 400w, ../../hidpi/resources/image-set-2x.png?2 800w,
+        resources/image-set-4x.png?2 1600w">
+    <source media="(max-width: 1600px)" sizes="1600px" srcset="../../hidpi/resources/image-set-1x.png?3 400w, ../../hidpi/resources/image-set-2x.png?3 800w,
+        resources/image-set-4x.png?3 1600w">
+    <img id="svg_type" src="resources/blue_rect.jpg?1">
+</picture>
 <!-- source with empty srcset - should be ignored -->
 <picture>
     <source media="(max-width: 400px)" sizes="400px" srcset="../../hidpi/resources/image-set-1x.png?1 400w, ../../hidpi/resources/image-set-2x.png?1 800w,