Web updates

HTML a4bb3465c868

Remove the concept of "dialog group" This change mechanically removes the concept of "dialog group", its definition, and its references. In doing so, the three focus fixup rules collapsed to one (now just named "focus fixup rule"), and the concept of "primary control group" became unnecessary. "Dialog group" was used to define the focusing behavior of nested dialogs (mainly for the non-modal case), but actual implementations don't follow that behavior. This is a step toward removing "control groups" completely, per #2171.

Takayoshi Kochi