Implement clone_content method

components/style/gecko/conversions.rs

@@ -919,3 +919,16 @@ impl<T> Rect<T> where T: GeckoStyleCoordConvertible {
         )
     }
 }
+
+/// Convert to String from given chars pointer.
+pub unsafe fn string_from_chars_pointer(p: *const u16) -> String {
+    use std::slice;
+    let mut length = 0;
+    let mut iter = p;
+    while *iter != 0 {
+        length += 1;
+        iter = iter.offset(1);
+    }
+    let char_vec = slice::from_raw_parts(p, length as usize);
+    String::from_utf16_lossy(char_vec)
+}