part of the fix for Bug #43661 --> need to register the browser as the handler for text/plain so we can open text documents

and have them get dispatched to the browser.
r=alecf

xpfe/browser/src/nsBrowserInstance.cpp

@@ -1620,6 +1620,7 @@ nsBrowserInstance::IsPreferred(const char * aContentType,
        || nsCRT::strcasecmp(aContentType, "image/jpeg") == 0
        || nsCRT::strcasecmp(aContentType, "image/png") == 0
        || nsCRT::strcasecmp(aContentType, "image/tiff") == 0
+       || nsCRT::strcasecmp(aContentType, "text/plain") == 0
        || nsCRT::strcasecmp(aContentType, "application/http-index-format") == 0)
        *aCanHandleContent = PR_TRUE;
   }
@@ -2269,6 +2270,11 @@ static nsModuleComponentInfo components[] = {
     NS_CONTENT_HANDLER_PROGID_PREFIX"text/css", 
     nsBrowserContentHandlerConstructor 
   },
+  { "Browser Content Handler",
+    NS_BROWSERCONTENTHANDLER_CID,
+    NS_CONTENT_HANDLER_PROGID_PREFIX"text/plain", 
+    nsBrowserContentHandlerConstructor 
+  },
   { "Browser Content Handler",
     NS_BROWSERCONTENTHANDLER_CID,
     NS_CONTENT_HANDLER_PROGID_PREFIX"image/gif",