Move DIALOG element tests to html/dialog/.

third_party/WebKit/LayoutTests/html/dialog/resources/dialog-layout.css

 /* Remove body margin and dialog styles for easier positioning expected values */
 body {
     height: 10000px;
     margin: 0;
 }
 
 dialog {
     border: 0;
     padding: 0;
     height: auto;
     width: auto;
 }
 
 #absolute-div {
     position: absolute;
     top: 800px;
     height: 50px;
     width: 90%;
 }
 
 #relative-div {
     position: relative;
     top: 20px;
     height: 30px;
 }