removed appendPrecisionModifier

skslc always provides support for precision modifiers (ignoring them if
unsupported on the target platform), so the Skia appendPrecisionModifier
function was redundant.

BUG=skia:

GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=5117

Change-Id: I4bcbd47ef8d1f4f1b055086d4c9050254584b48c
Reviewed-on: https://skia-review.googlesource.com/5117
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Ethan Nicholas <ethannicholas@google.com>
5 files changed