Make copying from script insets omit line numbers and breakpoint indicators.

runtime/observatory/lib/src/elements/script_inset.html

 <link rel="import" href="../../../../packages/polymer/polymer.html">
 <link rel="import" href="observatory_element.html">
 
 <polymer-element name="script-inset" extends="observatory-element">
   <template>
     <style>
       .sourceInset {
       }
       .sourceTable {
         display: table;
@@ skipping 28 matching lines @@
         width: 4em;
         text-align: right;
         color: #a8a8a8;
       }
       .hitsNotExecuted {
         background-color: #EEA7A7;
       }
       .hitsExecuted {
         background-color: #9BDD9B;
       }
-
+      .noCopy {}
       .emptyBreakpoint, .possibleBreakpoint, .busyBreakpoint, .unresolvedBreakpoint, .resolvedBreakpoint  {
         display: table-cell;
         vertical-align: top;
         font: 400 14px consolas, courier, monospace;
         width: 1em;
         text-align: center;
         cursor: pointer;
       }
       .possibleBreakpoint {
         color: #e0e0e0;
@@ skipping 13 matching lines @@
       }
       .resolvedBreakpoint {
         color: white;
         background-color: #e66;
       }
     </style>
   </template>
 </polymer-element>
 
 <script type="application/dart" src="script_inset.dart"></script>