DevTools: Add support for adding source map to a script from the DevTools window.

Source/devtools/front_end/sdk/CompilerScriptMapping.js

Index: Source/devtools/front_end/sdk/CompilerScriptMapping.js
diff --git a/Source/devtools/front_end/sdk/CompilerScriptMapping.js b/Source/devtools/front_end/sdk/CompilerScriptMapping.js
index 6e011be461f7ac7c7ce76d4252187aa7c411f194..24ee4983662fa6e89a48fa38977ff978021bb31a 100644
--- a/Source/devtools/front_end/sdk/CompilerScriptMapping.js
+++ b/Source/devtools/front_end/sdk/CompilerScriptMapping.js
@@ -107,6 +107,24 @@ WebInspector.CompilerScriptMapping.prototype = {
     addScript: function(script)
     {
         script.pushSourceMapping(this);
+        script.addEventListener(WebInspector.Script.Events.SourceMapURLAdded, this._sourceMapURLAdded.bind(this));
+        this._processScript(script);
+    },
+
+    /**
+     * @param {!WebInspector.Event} event
+     */
+    _sourceMapURLAdded: function(event)
+    {
+        var script = /** @type {!WebInspector.Script} */ (event.target);
+        this._processScript(script);
+    },
+
+    /**
+     * @param {!WebInspector.Script} script
+     */
+    _processScript: function(script)
+    {
         this.loadSourceMapForScript(script, sourceMapLoaded.bind(this));
 
         /**