Replace tests of ASSERT_ENABLED with ENABLE(ASSERT).

Source/platform/image-decoders/ImageFrame.cpp

Index: Source/platform/image-decoders/ImageFrame.cpp
diff --git a/Source/platform/image-decoders/ImageFrame.cpp b/Source/platform/image-decoders/ImageFrame.cpp
index 2708444e70c1fb854101ea8f5a778c6add374888..01dc5fff735d875c5bc713ee48830497ea4f9441 100644
--- a/Source/platform/image-decoders/ImageFrame.cpp
+++ b/Source/platform/image-decoders/ImageFrame.cpp
@@ -39,7 +39,7 @@ ImageFrame::ImageFrame()
     , m_premultiplyAlpha(true)
     , m_pixelsChanged(false)
     , m_requiredPreviousFrameIndex(kNotFound)
-#if ASSERT_ENABLED
+#if ENABLE(ASSERT)
     , m_requiredPreviousFrameIndexValid(false)
 #endif
 {
@@ -69,7 +69,7 @@ ImageFrame& ImageFrame::operator=(const ImageFrame& other)
     setHasAlpha(other.hasAlpha());
     // Copy raw fields to avoid ASSERT failure in requiredPreviousFrameIndex().
     m_requiredPreviousFrameIndex = other.m_requiredPreviousFrameIndex;
-#if ASSERT_ENABLED
+#if ENABLE(ASSERT)
     m_requiredPreviousFrameIndexValid = other.m_requiredPreviousFrameIndexValid;
 #endif
     return *this;