Assert that F16 is always treated as linear in SkColorSpaceXform

src/core/SkColorSpaceXform.cpp

Index: src/core/SkColorSpaceXform.cpp
diff --git a/src/core/SkColorSpaceXform.cpp b/src/core/SkColorSpaceXform.cpp
index f20886af7b11bd80e29e986b2df521ac41463f8e..2c5df2c5e287b1d5c84075c02a7da8edac7ea727 100644
--- a/src/core/SkColorSpaceXform.cpp
+++ b/src/core/SkColorSpaceXform.cpp
@@ -1115,6 +1115,9 @@ void SkColorSpaceXform_Base<kDst, kCSM>
 ::apply(void* dst, const uint32_t* src, int len, SkColorType dstColorType, SkAlphaType dstAlphaType)
 const
 {
+    // F16 is always treated as linear.
+    SkASSERT(kRGBA_F16_SkColorType != dstColorType || kLinear_SkGammaNamed == kDst);
+
     if (kFull_ColorSpaceMatch == kCSM) {
         switch (dstAlphaType) {
             case kPremul_SkAlphaType: