fix opacity check in SkBitmapDevice::Create

BUG=skia:4777
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1576453002

Review URL: https://codereview.chromium.org/1576453002

src/core/SkBitmapDevice.cpp

@@ -95,7 +95,7 @@ SkBitmapDevice* SkBitmapDevice::Create(const SkImageInfo& origInfo,
         if (!bitmap.setInfo(info)) {
             return nullptr;
         }
-    } else if (bitmap.info().isOpaque()) {
+    } else if (info.isOpaque()) {
         // If this bitmap is opaque, we don't have any sensible default color,
         // so we just return uninitialized pixels.
         if (!bitmap.tryAllocPixels(info)) {