go.talks: compile all code in editable code snippets
go.talks: compile all code in editable code snippets

Some elements of the DOM were being skipped over
because the existing algorithm assumed all the code
was inside SPAN tags. The browser "contenteditable"
feature introduces DIVs and probably other things.
The new algorithm is more liberal in what it accepts.

R=r, dsymonds
CC=golang-dev
https://codereview.appspot.com/14169043

bryanxu/go-zh.talks,d0f/go-zh.talks,bryanxu/go-zh.talks,bryanxu/go-zh.talks,d0f/go-zh.talks,webfd/go-zh.talks,d0f/go-zh.talks,webfd/go-zh.talks,webfd/go-zh.talks,webfd/go-zh.talks,d0f/go-zh.talks,bryanxu/go-zh.talks,bryanxu/go-zh.talks,bryanxu/go-zh.talks,d0f/go-zh.talks,webfd/go-zh.talks,d0f/go-zh.talks,webfd/go-zh.talks