Fix missing break statements.
Fix missing break statements.

Fixes:
 * conformance/glsl/functions/glsl-function*

BUG=angleproject:883

Change-Id: I22a528c6ba4c4077ba47269e14396b4117d1c849
Reviewed-on: https://chromium-review.googlesource.com/273169
Tested-by: Geoff Lang <b6fc25fe0362055230985c05cbfa8adb741ccc0f@chromium.org>
Reviewed-by: Brandon Jones <303ddc8529a3012e7fb187d611f08537af0cc183@chromium.org>

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