Fix trailing whitespace in .cpp, .h, and .idl files (ex. Source/core)

public/platform/WebRTCStatsRequest.h

Index: public/platform/WebRTCStatsRequest.h
diff --git a/public/platform/WebRTCStatsRequest.h b/public/platform/WebRTCStatsRequest.h
index 098050248ac466bbafc10595baad8e139fe8f250..8f9ad30f6909dc0fd6e847b3c2684394545ace7d 100644
--- a/public/platform/WebRTCStatsRequest.h
+++ b/public/platform/WebRTCStatsRequest.h
@@ -61,7 +61,7 @@ class WebRTCStatsResponse;
 //   size_t elementIndex = response.addElement(reportIndex, true, dateNow());
 //   For each statistic being reported on:
 //     response.addStatistic(reportIndex, true, elementIndex,
-//                           "name of statistic", "statistic value"); 
+//                           "name of statistic", "statistic value");
 //   Remote information (typically RTCP-derived) is added in the same way.
 // When finished adding information:
 // request.requestSucceeded(response);