Revert of Do not consolidate data in BMPImageDecoder

Source/platform/image-decoders/bmp/BMPImageReader.cpp

Index: Source/platform/image-decoders/bmp/BMPImageReader.cpp
diff --git a/Source/platform/image-decoders/bmp/BMPImageReader.cpp b/Source/platform/image-decoders/bmp/BMPImageReader.cpp
index 340c32c96f0f4dd69ab46d318df4b4ff50159931..8cbd07bf04386c7ebe77a3d325aec33f459e93c1 100644
--- a/Source/platform/image-decoders/bmp/BMPImageReader.cpp
+++ b/Source/platform/image-decoders/bmp/BMPImageReader.cpp
@@ -69,7 +69,6 @@ namespace blink {
 BMPImageReader::BMPImageReader(ImageDecoder* parent, size_t decodedAndHeaderOffset, size_t imgDataOffset, bool isInICO)
     : m_parent(parent)
     , m_buffer(0)
-    , m_fastReader(nullptr)
     , m_decodedOffset(decodedAndHeaderOffset)
     , m_headerOffset(decodedAndHeaderOffset)
     , m_imgDataOffset(imgDataOffset)
@@ -167,7 +166,6 @@ bool BMPImageReader::readInfoHeaderSize()
     ASSERT(m_decodedOffset == m_headerOffset);
     if ((m_decodedOffset > m_data->size()) || ((m_data->size() - m_decodedOffset) < 4))
         return false;
-
     m_infoHeader.biSize = readUint32(0);
     // Don't increment m_decodedOffset here, it just makes the code in
     // processInfoHeader() more confusing.
@@ -543,14 +541,13 @@ bool BMPImageReader::processColorTable()
     if ((m_decodedOffset > m_data->size()) || ((m_data->size() - m_decodedOffset) < tableSizeInBytes))
         return false;
     m_colorTable.resize(m_infoHeader.biClrUsed);
-
-    // On non-OS/2 1.x, an extra padding byte is present, which we need to skip.
-    const size_t bytesPerColor = m_isOS21x ? 3 : 4;
     for (size_t i = 0; i < m_infoHeader.biClrUsed; ++i) {
-        m_colorTable[i].rgbBlue = readUint8(0);
-        m_colorTable[i].rgbGreen = readUint8(1);
-        m_colorTable[i].rgbRed = readUint8(2);
-        m_decodedOffset += bytesPerColor;
+        m_colorTable[i].rgbBlue = m_data->data()[m_decodedOffset++];
+        m_colorTable[i].rgbGreen = m_data->data()[m_decodedOffset++];
+        m_colorTable[i].rgbRed = m_data->data()[m_decodedOffset++];
+        // Skip padding byte (not present on OS/2 1.x).
+        if (!m_isOS21x)
+            ++m_decodedOffset;
     }
 
     // We've now decoded all the non-image data we care about.  Skip anything
@@ -597,8 +594,8 @@ BMPImageReader::ProcessingResult BMPImageReader::processRLEData()
 
         // For every entry except EOF, we'd better not have reached the end of
         // the image.
-        const uint8_t count = readUint8(0);
-        const uint8_t code = readUint8(1);
+        const uint8_t count = m_data->data()[m_decodedOffset];
+        const uint8_t code = m_data->data()[m_decodedOffset + 1];
         if ((count || (code != 1)) && pastEndOfImage(0))
             return Failure;
 
@@ -632,8 +629,8 @@ BMPImageReader::ProcessingResult BMPImageReader::processRLEData()
 
                 // Fail if this takes us past the end of the desired row or
                 // past the end of the image.
-                const uint8_t dx = readUint8(2);
-                const uint8_t dy = readUint8(3);
+                const uint8_t dx = m_data->data()[m_decodedOffset + 2];
+                const uint8_t dy = m_data->data()[m_decodedOffset + 3];
                 if (dx || dy)
                     m_buffer->setHasAlpha(true);
                 if (((m_coord.x() + dx) > m_parent->size().width()) || pastEndOfImage(dy))
@@ -673,7 +670,7 @@ BMPImageReader::ProcessingResult BMPImageReader::processRLEData()
                     return InsufficientData;
 
                 // One BGR triple that we copy |count| times.
-                fillRGBA(endX, readUint8(3), readUint8(2), code, 0xff);
+                fillRGBA(endX, m_data->data()[m_decodedOffset + 3], m_data->data()[m_decodedOffset + 2], code, 0xff);
                 m_decodedOffset += 4;
             } else {
                 // RLE8 has one color index that gets repeated; RLE4 has two
@@ -736,7 +733,7 @@ BMPImageReader::ProcessingResult BMPImageReader::processNonRLEData(bool inRLE, i
             // the most significant bits in the byte).
             const uint8_t mask = (1 << m_infoHeader.biBitCount) - 1;
             for (size_t byte = 0; byte < unpaddedNumBytes; ++byte) {
-                uint8_t pixelData = readUint8(byte);
+                uint8_t pixelData = m_data->data()[m_decodedOffset + byte];
                 for (size_t pixel = 0; (pixel < pixelsPerByte) && (m_coord.x() < endX); ++pixel) {
                     const size_t colorIndex = (pixelData >> (8 - m_infoHeader.biBitCount)) & mask;
                     if (m_decodingAndMask) {