avoid leaking original opacity dictionary(cherry picked from commit 9707fb0)

Author: ssp

Plugin/Plugin.m

@@ -462,6 +462,7 @@ - (void)webPlugInDestroy
 	[self setWebView:nil];
 	[self setBaseURL:nil];
 	[self setAttributes:nil];
+	[self setOriginalOpacityAttributes:nil];
 
 	[_flashVars release];
 	_flashVars = nil;