DevTools: add tests to fixate sourcemap bindings behavior

third_party/WebKit/Source/devtools/front_end/bindings/SASSSourceMapping.js

Index: third_party/WebKit/Source/devtools/front_end/bindings/SASSSourceMapping.js
diff --git a/third_party/WebKit/Source/devtools/front_end/bindings/SASSSourceMapping.js b/third_party/WebKit/Source/devtools/front_end/bindings/SASSSourceMapping.js
index 70128902e708b2814e441ee56c0e10b8923eba00..20f461d32d50d3232912c2e90b417e7eee207b9b 100644
--- a/third_party/WebKit/Source/devtools/front_end/bindings/SASSSourceMapping.js
+++ b/third_party/WebKit/Source/devtools/front_end/bindings/SASSSourceMapping.js
@@ -49,6 +49,12 @@ Bindings.SASSSourceMapping = class {
   }
 
   /**
+   * @param {?SDK.SourceMap} sourceMap
+   */
+  _sourceMapAttachedForTest(sourceMap) {
+  }
+
+  /**
    * @param {!Common.Event} event
    */
   _sourceMapAttached(event) {
@@ -62,6 +68,7 @@ Bindings.SASSSourceMapping = class {
           contentProvider, SDK.ResourceTreeFrame.fromStyleSheet(header), false, embeddedContentLength);
     }
     Bindings.cssWorkspaceBinding.updateLocations(header);
+    this._sourceMapAttachedForTest(sourceMap);
   }
 
   /**