https://bugs.webkit.org/show_bug.cgi?id=79715

Reviewed by Jian Li.

Source/WebCore:

Test: fast/files/file-reader-directory-crash.html

* platform/SharedBuffer.cpp: (WebCore::SharedBuffer::SharedBuffer): Crash early if a caller
mixed up in-band error signal with length again.

* platform/network/BlobResourceHandle.cpp:
(WebCore): Changed errors into an enum. Added a proper domain for blob errors.
(WebCore::BlobResourceHandle::didReceiveResponse): There is already a constant for INT_MAX
in C/C++.
(WebCore::BlobResourceHandle::didRead): Don't send "-1" for failure down the success path.
(WebCore::BlobResourceHandle::notifyFail): Use a proper domain for blob errors, and a non-
empty message.

LayoutTests:

* fast/files/file-reader-directory-crash-expected.txt: Added.
* fast/files/file-reader-directory-crash.html: Added.


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@109132 268f45cc-cd09-0410-ab3c-d52691b4dbfc