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

Source/modules/encryptedmedia/MediaKeyMessageEvent.idl

Index: Source/modules/encryptedmedia/MediaKeyMessageEvent.idl
diff --git a/Source/modules/encryptedmedia/MediaKeyMessageEvent.idl b/Source/modules/encryptedmedia/MediaKeyMessageEvent.idl
index 513b910568a4d2520647e7e45f6699c1d4d23526..4b12d9b9f254d1dfb4a9bd77784e178d845e7d7f 100644
--- a/Source/modules/encryptedmedia/MediaKeyMessageEvent.idl
+++ b/Source/modules/encryptedmedia/MediaKeyMessageEvent.idl
@@ -20,13 +20,13 @@
  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
  * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
- * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 [
     Conditional=ENCRYPTED_MEDIA_V2,
     EnabledAtRuntime=encryptedMedia,
-    ConstructorTemplate=Event 
+    ConstructorTemplate=Event
 ] interface MediaKeyMessageEvent : Event {
     readonly attribute Uint8Array message;
     [InitializedByEventConstructor] readonly attribute DOMString destinationURL;