[WIP] Supporting arm_neon_optional flag for blink platform.

Source/platform/graphics/cpu/arm/filters/FECompositeArithmeticNEON.h

 /*
  * Copyright (C) 2011 University of Szeged
  * Copyright (C) 2011 Felician Marton
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
@@ skipping 54 matching lines @@
             result = vaddq_f32(result, k4x4);
 
         // Convert result to uint so negative values are converted to zero.
         uint16x4_t temporary3 = vmovn_u32(vminq_u32(vcvtq_u32_f32(result), max255));
         uint8x8_t temporary4 = vmovn_u16(vcombine_u16(temporary3, temporary3));
         *destinationPixel++ = vget_lane_u32(vreinterpret_u32_u8(temporary4), 0);
         ++sourcePixel;
     }
 }
 
-inline void FEComposite::platformArithmeticNeon(unsigned char* source, unsigned char* destination,
-    unsigned pixelArrayLength, float k1, float k2, float k3, float k4)
+inline void FEComposite::arithmeticSoftwareNEON(unsigned char* source, unsigned char* destination,
+    int pixelArrayLength, float k1, float k2, float k3, float k4)
 {
+    ASSERT(!(pixelArrayLength & 0x3));
+
     if (!k4) {
         if (!k1) {
-            computeArithmeticPixelsNeon<0, 0>(source, destination, pixelArrayLength, k1, k2, k3, k4);
+            computeArithmeticPixelsNeon<0, 0>(source, destination, static_cast<unsigned>(pixelArrayLength), k1, k2, k3, k4);
             return;
         }
 
-        computeArithmeticPixelsNeon<1, 0>(source, destination, pixelArrayLength, k1, k2, k3, k4);
+        computeArithmeticPixelsNeon<1, 0>(source, destination, static_cast<unsigned>(pixelArrayLength), k1, k2, k3, k4);
         return;
     }
 
     if (!k1) {
-        computeArithmeticPixelsNeon<0, 1>(source, destination, pixelArrayLength, k1, k2, k3, k4);
+        computeArithmeticPixelsNeon<0, 1>(source, destination, static_cast<unsigned>(pixelArrayLength), k1, k2, k3, k4);
         return;
     }
-    computeArithmeticPixelsNeon<1, 1>(source, destination, pixelArrayLength, k1, k2, k3, k4);
+    computeArithmeticPixelsNeon<1, 1>(source, destination, static_cast<unsigned>(pixelArrayLength), k1, k2, k3, k4);
 }
 
 } // namespace blink
 
 #endif // HAVE(ARM_NEON_INTRINSICS)
 
 #endif // FECompositeArithmeticNEON_h