Avoid srcset resource download when higher density resource is in cache.

LayoutTests/fast/dom/HTMLImageElement/image-sizes-1x-expected.txt

 PASS successfullyParsed is true
 
 TEST COMPLETE
 PASS document.getElementById("simple").currentSrc.indexOf("file://") == 0 is true
 PASS document.getElementById("simple").clientWidth is (window.innerWidth)
-PASS currentSrcFileName("simple") is "image-set-2x.png"
+PASS currentSrcFileNameNoParams("simple") is "image-set-2x.png"
 PASS document.getElementById("small_sizes").clientWidth is 300
-PASS currentSrcFileName("small_sizes") is "image-set-1x.png"
+PASS currentSrcFileNameNoParams("small_sizes") is "image-set-1x.png"
 PASS document.getElementById("sizes_x_descriptors").clientWidth is 400
-PASS currentSrcFileName("sizes_x_descriptors") is "image-set-1x.png"
+PASS currentSrcFileNameNoParams("sizes_x_descriptors") is "image-set-1x.png"
 PASS document.getElementById("sizes_src").clientWidth is 400
-PASS currentSrcFileName("sizes_src") is "image-set-1x.png"
+PASS currentSrcFileNameNoParams("sizes_src") is "image-set-1x.png"
 PASS document.getElementById("default_sizes").clientWidth is window.innerWidth
-PASS currentSrcFileName("default_sizes") is "image-set-2x.png"
+PASS currentSrcFileNameNoParams("default_sizes") is "image-set-2x.png"
 PASS document.getElementById("invalid_length").clientWidth is window.innerWidth
-PASS currentSrcFileName("invalid_length") is "image-set-2x.png"
+PASS currentSrcFileNameNoParams("invalid_length") is "image-set-2x.png"
 PASS document.getElementById("src_and_w").clientWidth is within 0.015625 of 700
-PASS currentSrcFileName("src_and_w") is "image-set-4x.png"
+PASS currentSrcFileNameNoParams("src_and_w") is "image-set-4x.png"
 PASS document.getElementById("src_and_w2").clientWidth is within 0.015625 of 700
-PASS currentSrcFileName("src_and_w2") is "image-set-1x.png"
+PASS currentSrcFileNameNoParams("src_and_w2") is "image-set-1x.png"
 PASS document.getElementById("x_and_w").clientWidth is within 0.015625 of 700
-PASS currentSrcFileName("x_and_w") is "image-set-4x.png"
+PASS currentSrcFileNameNoParams("x_and_w") is "image-set-4x.png"
 PASS document.getElementById("x_and_w2").clientWidth is 400
-PASS currentSrcFileName("x_and_w2") is "image-set-2x.png"
+PASS currentSrcFileNameNoParams("x_and_w2") is "image-set-2x.png"
 PASS document.getElementById("x_and_w3").clientWidth is 400
-PASS currentSrcFileName("x_and_w3") is "image-set-2x.png"
+PASS currentSrcFileNameNoParams("x_and_w3") is "image-set-2x.png"
 PASS document.getElementById("half_size").clientWidth is (window.innerWidth/2)
-PASS currentSrcFileName("half_size") is "image-set-2x.png"
+PASS currentSrcFileNameNoParams("half_size") is "image-set-2x.png"
 PASS document.getElementById("infitisimal_sizes").clientWidth is (window.innerWidth/100)
-PASS currentSrcFileName("infitisimal_sizes") is "image-set-2x.png"
-PASS currentSrcFileName("fraction") is "data:,a"
-              
+PASS currentSrcFileNameNoParams("infitisimal_sizes") is "image-set-2x.png"
+PASS currentSrcFileNameNoParams("fraction") is "data:,a"
+PASS document.getElementById("seen_lowest_before").clientWidth is 1600
+PASS currentSrcFileNameNoParams("seen_lowest_before") is "image-set-4x.png"
+PASS document.getElementById("seen_highest_before").clientWidth is 800
+PASS currentSrcFileNameNoParams("seen_highest_before") is "image-set-4x.png"
+