But is it really an hour? I doubt that Apple uploads the code they actually used: it's likely that code, and then lots of removed components that would reveal too much about how something works (e.g. there are no build scripts or Xcode projects for JavaScriptCore releases, only the code itself).
At least, they would need to make sure that none of their proprietary code slips out. That likely involves more than "svn checkout; tar; ftp", maybe even lawyers to check it.
"For a library, complete source code means all the source code for all modules it contains, plus any associated interface definition files, plus the scripts used to control compilation and installation of the library."
They don't. Well, they might, but not an iOS binary. There's Makefiles for Android and (I believe) the desktop, but nothing setup for use with the iPhone SDK.
In addition to what openbear pointed out, it should be noted that the GPL requires build scripts to be included with the source. (What good would source do anybody without the three-bajillion-line Makefile that builds it?) GPLv3 also extends this to stuff needed to run the code on the hardware it's intended for (like tools to sign binaries so they'll run on locked-down embedded platforms like phones or DVRs).
There's a practical aspect to the GPL, here. The spirit of the license is, "if I can't view, modify, build, use, and redistribute the software, it's a violation."
components that would reveal too much about how something works
It is a significant violation of the spirit of open source to try to keep others from understanding how things work. Mobile Safari may be a competitive advantage for Apple, but the advantages are in the UI, not JavaScriptCore. Google already has a pretty decent JS engine of its own, after all.
At least, they would need to make sure that none of their proprietary code slips out. That likely involves more than "svn checkout; tar; ftp", maybe even lawyers to check it.