html: Use existing standard library interface internally.
html: Use existing standard library interface internally.

Now that Go 1.1 is out, commit 3651a440a70063fcb7028c5f214b0ffb20b3770d
can be reverted.

Change-Id: I7ac8478aafaa5067630e99cec9eca59792107892
Reviewed-on: https://go-review.googlesource.com/11612
Reviewed-by: Brad Fitzpatrick <ae9783c0b0efc69cd85ab025ddd17aa44cdc4aa5@golang.org>

golang/net,cmars/tools,subuk/net,cesanta/goxnet,muzining/net,albertjin/golang-net,mckinney-subgraph/net,flowlo/go-net,albertjin/golang-net,cesanta/goxnet,yangxianjun/net,yangxianjun/net,DramaFever/golang.org-x-net,dafyddcrosby/net,raboof/net,kiip/net,dafyddcrosby/net,subuk/net,zabawaba99/net,DramaFever/golang.org-x-net,w4ngyi/net,flowlo/go-net,mckinney-subgraph/net,cmars/tools,gomini/net,zabawaba99/net,kiip/net,muzining/net,veliamsli/net,gomini/net,w4ngyi/net,cmars/tools,raboof/net,cmars/tools,veliamsli/net