No: the mobile version of WebCore is different, and for example comes with binary object blobs (which is sufficient for LGPL compliance) for source code that Apple refuses to provide as open source. I wish I had been here earlier to correct this misinformation :/ (though I'm also glad I've gotten in the habit of not checking Hacker News after I comment). Note the libWebCore_{Sim,armv7,armv7s}.a that is provided in the WebCore source repository at opensource.apple.com.
It is also simply not sufficient to say "here is a repository with a lot of code in it": you have to be able to specify what exact code was used for the build (which is what I care about, as I'm constantly trying to analyze the version of WebCore on the device: I have no interest in compiling my own copy or building my own browser), and it is not the main WebCore repository's job to keep tags or branches around for specific versions of iOS that Apple distributes.
http://www.opensource.apple.com/source/WebCore/WebCore-1640....
It is also simply not sufficient to say "here is a repository with a lot of code in it": you have to be able to specify what exact code was used for the build (which is what I care about, as I'm constantly trying to analyze the version of WebCore on the device: I have no interest in compiling my own copy or building my own browser), and it is not the main WebCore repository's job to keep tags or branches around for specific versions of iOS that Apple distributes.