So is the issue here that they have not packaged it up for people and put it on opensource.apple.com? Is the source not available in the official repository at webkit.org?
No, it isn't: Apple uses a modified version of WebKit and WebCore for iOS that is not present in trunk. For WebKit they are allowed to hold back these changes, but for WebCore they are not. They do anyway, however, and have actually /never/ provided a copy of WebCore for iOS that is complete enough to compile (in particular, the code for WAK* is redacted).