Checking if frame is complete and access duration doesn't need a decode

Source/core/platform/image-decoders/gif/GIFImageReader.h

Index: Source/core/platform/image-decoders/gif/GIFImageReader.h
diff --git a/Source/core/platform/image-decoders/gif/GIFImageReader.h b/Source/core/platform/image-decoders/gif/GIFImageReader.h
index bda8997d9db128d71759a269f3f5d45949767894..b2cefbe74395e1f2e2c7f56a7f512bb210cba8e8 100644
--- a/Source/core/platform/image-decoders/gif/GIFImageReader.h
+++ b/Source/core/platform/image-decoders/gif/GIFImageReader.h
@@ -282,11 +282,13 @@ public:
         return frame->isLocalColormapDefined ? frame->localColormapSize : 0;
     }
 
-    const GIFFrameContext* frameContext() const
+    const GIFFrameContext* frameContext(size_t index) const
     {
-        return m_currentDecodingFrame < m_frames.size() ? m_frames[m_currentDecodingFrame].get() : 0;
+        return index < m_frames.size() ? m_frames[index].get() : 0;
     }
 
+    bool parseCompleted() const { return m_parseCompleted; }
+
 private:
     bool parse(size_t dataPosition, size_t len, bool parseSizeOnly);
     void setRemainingBytes(size_t);