Add spm support
Use Element.matches if available

Spec:
http://dom.spec.whatwg.org/#dom-element-matches

Support in Chromium:
https://code.google.com/p/chromium/issues/detail?id=326652
Support instanceof d3.{color,rgb,…}

This also makes it possible to create a subclass of d3.color outside of the core
library, which would then support automatic interpolation.
Revert "Remove workaround for WebKit bug 44083."

This reverts commit 2b148070553c9493cae01d4960d283ec5bdf957f.

Fixes #1903.
selection.classed: coerce name to string.

Fixes #1625.
Merge branch 'instanceof-color' into 3.4.9
Use element.matches if available.
Merge branch 'foolip-matches' into 3.4.9
Merge branch 'classed' into 3.4.9
Merge branch 'spmjs-master' into 3.4.9
Merge branch '3.4.9'
Fix #1933 - set zoom center on zoomstart.

Rather than set the zoom center on the first mousewheel following a mousemove,
we now set the zoom center on the first mousewheel event of a zoom gesture. This
is slightly simpler logic and avoids confusing behavior during constrained
momentum scrolling.