WebKit: out-of-bounds read in WebCore::SVGPatternElement::collectPatternAttributes(CVE-2017-13783)

There is an out-of-bounds read security vulnerability in WebKit. The vulnerability was confirmed on ASan build of WebKit nightly. ASan log: ================================================================= ==30453==ERROR: AddressSanitizer: heap-buffer-overflow on address 0x61200007e474 at pc...