Fix non-text copying for Safari with -webkit-user-select: none. Add…

…resses #75.

clipboard-polyfill.ts

@@ -176,6 +176,9 @@ function copyUsingTempSelection(e: HTMLElement, data: DT): boolean {
 // rejected.
 function copyUsingTempElem(data: DT): boolean {
   var tempElem = document.createElement("div");
+  // Setting an individual property does not support `!important`, so we set the
+  // whole style instead of just the `-webkit-user-select` property.
+  tempElem.setAttribute("style", "-webkit-user-select: text !important");
   // Place some text in the elem so that Safari has something to select.
   tempElem.textContent = "temporary element";
   document.body.appendChild(tempElem);

test/manual/safari-user-select.html

@@ -19,7 +19,10 @@
 }
 function test() {
   try {
-    clipboard.writeText("Safari user select test").then(
+    var dt = new clipboard.DT();
+    dt.setData("text/html", "<i>Markup</i> <b>text</b>. Paste me into a rich text editor.");
+    dt.setData("text/plain", "Fallback markup text. Paste me into a rich text editor.");
+    clipboard.write(dt).then("Safari user select test").then(
       reportResult.bind(this, "PASS"),
       function(e) {
         reportResult("FAIL (after promise): ", e);