MacOSX: Change the two dummy messages to use systemUpTime as timestamp to fix CEF renderer process crash.

Begin with Chromium 97, EventLatencyTracingRecorder was added to trace the performance.
And the timestamp 0 used will lead to 'DCHECK(!dispatch_timestamp.is_null());' in function
EventLatencyTracingRecorder::RecordEventLatencyTraceEvent
see:
https://github.com/chromium/chromium/blob/109.0.5414.120/cc/metrics/event_latency_tracing_recorder.cc

Way to reproduce the crash:
Right click to popup the context-menu created by CEF.
Then the CEF renderer process will crash.

Set the timestamp to [[NSProcessInfo processInfo] systemUptime] to fix it.

Author: 徐扬斌

src/osx/cocoa/evtloop.mm

@@ -380,7 +380,7 @@ static NSUInteger CalculateNSEventMaskFromEventCategory(wxEventCategory cat)
         NSEvent *event = [NSEvent otherEventWithType:NSApplicationDefined 
                                         location:NSMakePoint(0.0, 0.0) 
                                    modifierFlags:0 
-                                       timestamp:0 
+                                       timestamp:[[NSProcessInfo processInfo] systemUptime] 
                                     windowNumber:0 
                                          context:nil
                                          subtype:0 data1:0 data2:0]; 

src/osx/cocoa/utils.mm

@@ -409,7 +409,7 @@ - (void)sendEvent:(NSEvent *)anEvent
         NSEvent *event = [NSEvent otherEventWithType:NSApplicationDefined
                                     location:NSMakePoint(0.0, 0.0)
                                modifierFlags:0
-                                   timestamp:0
+                                   timestamp:[[NSProcessInfo processInfo] systemUptime]
                                 windowNumber:0
                                      context:nil
                                      subtype:0 data1:0 data2:0];