Revert of remove colorfilter native-565 support. complicating w/ no real value.

src/core/SkFilterShader.cpp

Index: src/core/SkFilterShader.cpp
diff --git a/src/core/SkFilterShader.cpp b/src/core/SkFilterShader.cpp
index a10a7c9d77b0fb2bbcede4d71b3f5f81a1bbaab9..48c4b8b477314ba2fbf9a6e64a5859754c7023d7 100644
--- a/src/core/SkFilterShader.cpp
+++ b/src/core/SkFilterShader.cpp
@@ -46,12 +46,13 @@
     uint32_t shaderF = fShaderContext->getFlags();
     uint32_t filterF = filterShader.fFilter->getFlags();
 
-    // filters don't support 16bit, so clear the matching bit in the shader
-    shaderF &= ~SkShader::kHasSpan16_Flag;
-
+    // if the filter doesn't support 16bit, clear the matching bit in the shader
+    if (!(filterF & SkColorFilter::kHasFilter16_Flag)) {
+        shaderF &= ~SkShader::kHasSpan16_Flag;
+    }
     // if the filter might change alpha, clear the opaque flag in the shader
     if (!(filterF & SkColorFilter::kAlphaUnchanged_Flag)) {
-        shaderF &= ~SkShader::kOpaqueAlpha_Flag;
+        shaderF &= ~(SkShader::kOpaqueAlpha_Flag | SkShader::kHasSpan16_Flag);
     }
     return shaderF;
 }
@@ -86,6 +87,16 @@
     filterShader.fFilter->filterSpan(result, count, result);
 }
 
+void SkFilterShader::FilterShaderContext::shadeSpan16(int x, int y, uint16_t result[], int count) {
+    const SkFilterShader& filterShader = static_cast<const SkFilterShader&>(fShader);
+
+    SkASSERT(fShaderContext->getFlags() & SkShader::kHasSpan16_Flag);
+    SkASSERT(filterShader.fFilter->getFlags() & SkColorFilter::kHasFilter16_Flag);
+
+    fShaderContext->shadeSpan16(x, y, result, count);
+    filterShader.fFilter->filterSpan16(result, count, result);
+}
+
 #ifndef SK_IGNORE_TO_STRING
 void SkFilterShader::toString(SkString* str) const {
     str->append("SkFilterShader: (");