Emit 4 byte UTF-sequences in place of encoded surrogate pairs.

Symmetric with a5afcfc73141e5e378d79a326d0 which converts 4 byte UTF-8
sequences to surrogate pairs.

bug: 18848397

Change-Id: I42adc275b7e0df0cbbd9d8a799e8b0447d8f5cae
3 files changed