Fix bug testing SkCodec for ICO
Fix bug testing SkCodec for ICO

Looking in Gold, I see some ICO images that only show the upper left
corner of the originals. It is happening because we use different ways
of deciding what the dimensions are:

In CodecSrc::size(), we use an SkScaledCodec to get the dimensions,
even when fMode is not kScaledCodec_Mode.

In CodecSrc::draw(), we only use SkScaledCodec in kScaledCodec_Mode.

My recent CL to combine SkScanlineDecoder with SkCodec revealed this
bug, because now SkScaledCodec::NewFromStream will succeed on ICO.
(Previously, it failed because we do not yet have a scanline decoder
for ICO (skbug.com/4404). Now that they are combined, we would need
to specially flag ICO to stop returning an SkScaledCodec.)

Switch size() to use the correct type of codec.

Review URL: https://codereview.chromium.org/1373253004

tmpvar/skia.cc,google/skia,Hikari-no-Tenshi/android_external_skia,google/skia,rubenvb/skia,HalCanary/skia-hc,HalCanary/skia-hc,HalCanary/skia-hc,aosp-mirror/platform_external_skia,qrealka/skia-hc,qrealka/skia-hc,aosp-mirror/platform_external_skia,tmpvar/skia.cc,google/skia,qrealka/skia-hc,rubenvb/skia,rubenvb/skia,google/skia,Hikari-no-Tenshi/android_external_skia,qrealka/skia-hc,Hikari-no-Tenshi/android_external_skia,qrealka/skia-hc,Hikari-no-Tenshi/android_external_skia,aosp-mirror/platform_external_skia,rubenvb/skia,rubenvb/skia,aosp-mirror/platform_external_skia,aosp-mirror/platform_external_skia,tmpvar/skia.cc,aosp-mirror/platform_external_skia,tmpvar/skia.cc,qrealka/skia-hc,rubenvb/skia,qrealka/skia-hc,tmpvar/skia.cc,Hikari-no-Tenshi/android_external_skia,google/skia,HalCanary/skia-hc,aosp-mirror/platform_external_skia,tmpvar/skia.cc,rubenvb/skia,aosp-mirror/platform_external_skia,google/skia,tmpvar/skia.cc,tmpvar/skia.cc,rubenvb/skia,google/skia,aosp-mirror/platform_external_skia,qrealka/skia-hc,HalCanary/skia-hc,HalCanary/skia-hc,Hikari-no-Tenshi/android_external_skia,HalCanary/skia-hc,rubenvb/skia,rubenvb/skia,tmpvar/skia.cc,Hikari-no-Tenshi/android_external_skia,google/skia,aosp-mirror/platform_external_skia,google/skia,HalCanary/skia-hc,HalCanary/skia-hc,google/skia,HalCanary/skia-hc,Hikari-no-Tenshi/android_external_skia