Move all filters-related files from core/platform to platform.

Source/platform/graphics/filters/SourceAlpha.h

Index: Source/platform/graphics/filters/SourceAlpha.h
diff --git a/Source/core/platform/graphics/filters/SourceAlpha.h b/Source/platform/graphics/filters/SourceAlpha.h
similarity index 95%
rename from Source/core/platform/graphics/filters/SourceAlpha.h
rename to Source/platform/graphics/filters/SourceAlpha.h
index 3a60df63ce84d02ed0b46b9c7f890e3550c2cf8b..519a31af32f9ccd11cac8787250ec4660b7e9754 100644
--- a/Source/core/platform/graphics/filters/SourceAlpha.h
+++ b/Source/platform/graphics/filters/SourceAlpha.h
@@ -26,7 +26,7 @@
 
 namespace WebCore {
 
-class SourceAlpha : public FilterEffect {
+class PLATFORM_EXPORT SourceAlpha : public FilterEffect {
 public:
     static PassRefPtr<SourceAlpha> create(Filter*);
 
@@ -47,6 +47,6 @@ private:
     virtual void applySoftware() OVERRIDE;
 };
 
-} //namespace WebCore
+} // namespace WebCore
 
 #endif // SourceAlpha_h