clean up some SK_LEGACY... defines

Change-Id: I86c9f983672e6edd616afe003ea9823da7890511
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/290585
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: Mike Klein <mtklein@google.com>
diff --git a/src/core/SkColorSpaceXformSteps.cpp b/src/core/SkColorSpaceXformSteps.cpp
index 133d661..8e8a2e1 100644
--- a/src/core/SkColorSpaceXformSteps.cpp
+++ b/src/core/SkColorSpaceXformSteps.cpp
@@ -132,9 +132,6 @@
 }
 
 void SkColorSpaceXformSteps::apply(SkRasterPipeline* p, bool src_is_normalized) const {
-#if defined(SK_LEGACY_SRGB_STAGE_CHOICE)
-    src_is_normalized = true;
-#endif
     if (flags.unpremul) { p->append(SkRasterPipeline::unpremul); }
     if (flags.linearize) {
         if (src_is_normalized && srcTF_is_sRGB) {
diff --git a/src/opts/SkRasterPipeline_opts.h b/src/opts/SkRasterPipeline_opts.h
index 7e9558e..339d7a8 100644
--- a/src/opts/SkRasterPipeline_opts.h
+++ b/src/opts/SkRasterPipeline_opts.h
@@ -978,11 +978,7 @@
 }
 
 SI F approx_powf(F x, F y) {
-#if defined(SK_LEGACY_APPROX_POWF_SPECIALCASE)
-    return if_then_else((x == 0)         , 0
-#else
     return if_then_else((x == 0)|(x == 1), x
-#endif
                                          , approx_pow2(approx_log2(x) * y));
 }