The file was generated from the mimeMap in %System32%\inetsrv\config\applicationHost.config and it looks like IIS 8 has some slightly different mime mappings. It should probably be updated to match this file although the utility of it is highly questionable.
Comments: Adding more context for the bug: The WebPages’ “MimeMapping.cs” file is originally engineered based on the “ApplicationHost.config” file from IIS 7.5. The newly released IIS8.0 has some minor change in the ApplicationHost.config file which cause some mismatch entry from the MimeMapping.cs in WebPages. The usage that potentially would impact is the System.Web.Helper e.g. the System.Image class; the other possible usage is the WebPage Administration. The entry pointed out by the report is actually boils down to one line of code; the difference is listed below: From MimeMapping.cs: { ".js", "application/x-javascript" }, From the new ApplicationHost.config: <mimeMap fileExtension=".js" mimeType="application/javascript" />
Comments: Adding more context for the bug: The WebPages’ “MimeMapping.cs” file is originally engineered based on the “ApplicationHost.config” file from IIS 7.5. The newly released IIS8.0 has some minor change in the ApplicationHost.config file which cause some mismatch entry from the MimeMapping.cs in WebPages. The usage that potentially would impact is the System.Web.Helper e.g. the System.Image class; the other possible usage is the WebPage Administration. The entry pointed out by the report is actually boils down to one line of code; the difference is listed below: From MimeMapping.cs: { ".js", "application/x-javascript" }, From the new ApplicationHost.config: <mimeMap fileExtension=".js" mimeType="application/javascript" />