Fix internalize case for Date into time.Time struct.
Fix internalize case for Date into time.Time struct.

Fixes #287.

bpowers/gopherjs,govlas/gopherjs,albrow/gopherjs,gopherjs/gopherjs,gopherjs/gopherjs,Yanjing123/gopherjs,govlas/gopherjs,Archs/gopherjs,gopherjs/gopherjs,flimzy/gopherjs,jargv/gopherjs,jargv/gopherjs,flimzy/gopherjs,bpowers/gopherjs,gopherjs/gopherjs,Yanjing123/gopherjs,Archs/gopherjs,bpowers/gopherjs,govlas/gopherjs,jargv/gopherjs,Archs/gopherjs,Yanjing123/gopherjs,albrow/gopherjs,flimzy/gopherjs,gopherjs/gopherjs,albrow/gopherjs