Gentoo's Bugzilla –
Attachment 680236 Details for
Bug 708426net-libs/webkit-gtk-2.26.3 with sys-libs/musl : .../work/webkitgtk-2.26.3/Source/JavaScriptCore/runtime/SamplingProfiler.cpp:379:48: error: ‘framePointer’ is not a member of ‘JSC::MachineContext’