No other browser I can find supports this anyway. *We* don't even successfully display the image, but we try to.
Created attachment 198207 [details]
Not sure if this is a reasonable place to bail if we find PDF data, but... maybe?
Attachment 198207 [details] did not pass style-queue:
Failed to run "['Tools/Scripts/check-webkit-style', '--diff-files', u'Source/WebCore/ChangeLog', u'Source/WebCore/loader/icon/IconLoader.cpp']" exit_code: 1
Source/WebCore/loader/icon/IconLoader.cpp:100: Omit int when using unsigned [runtime/unsigned] 
Source/WebCore/loader/icon/IconLoader.cpp:104: Tests for true/false, null/non-null, and zero/non-zero should all be done without equality comparisons. [readability/comparison_to_zero] 
Total errors found: 2 in 2 files
If any of these errors are false positives, please file a bug against check-webkit-style.
Created attachment 198208 [details]
Created attachment 198209 [details]
Created attachment 198210 [details]
Comment on attachment 198210 [details]
View in context: https://bugs.webkit.org/attachment.cgi?id=198210&action=review
> + static const char* pdfMagicNumber = "%PDF";
> + static unsigned pdfMagicNumberLength = strlen(pdfMagicNumber);
I would have done this with a uint32_t constant (and gotten it wrong on big endian) or a char array that I could sizeof() instead of using strlen().