fix warnings on Mac in experimental

Fix these class of warnings:
- unused functions
- unused locals
- sign mismatch
- missing function prototypes
- missing newline at end of file
- 64 to 32 bit truncation

The changes prefer to link in dead code in the debug build
with 'if (false)' than to comment it out, but trivial cases
are commented out or sometimes deleted if it appears to be
a copy/paste error.
Review URL: https://codereview.appspot.com/6307044

git-svn-id: http://skia.googlecode.com/svn/trunk@4187 2bbb7eff-a529-9590-31e7-b0007b416f81

experimental/Debugger/SkDebugDumper.h

@@ -35,4 +35,4 @@ private:
     
     typedef SkDumpCanvas::Dumper INHERITED;
 };
-#endif
+#endif

experimental/SkSetPoly3To3.cpp

@@ -7,6 +7,9 @@
  */
 #include "SkMatrix.h"
 
+// FIXME: needs to be in a header
+bool SkSetPoly3To3(SkMatrix* matrix, const SkPoint src[3], const SkPoint dst[3]);
+
 static void computeOuterProduct(SkScalar op[4],
                                 const SkPoint pts0[3], const SkPoint& ave0,
                                 const SkPoint pts1[3], const SkPoint& ave1) {

experimental/SkSetPoly3To3_A.cpp

@@ -7,6 +7,9 @@
  */
 #include "SkMatrix.h"
 
+// FIXME: needs to be in a header
+bool SkSetPoly3To3_A(SkMatrix* matrix, const SkPoint src[3], const SkPoint dst[3]);
+
 #ifdef SK_SCALAR_IS_FIXED
     typedef int64_t SkDScalar;
 

experimental/SkSetPoly3To3_D.cpp

@@ -7,6 +7,9 @@
  */
 #include "SkMatrix.h"
 
+// FIXME: needs to be in a header
+bool SkSetPoly3To3_D(SkMatrix* matrix, const SkPoint src[3], const SkPoint dst[3]);
+
 typedef int64_t SkDScalar;
 
 static SkScalar SkDScalar_toScalar(SkDScalar value) {
@@ -17,7 +20,7 @@ static SkScalar SkDScalar_toScalar(SkDScalar value) {
 }
 
 static SkDScalar SkDScalar_setMul(SkScalar a, SkScalar b) {
-    return (SkDScalar) ((SkDScalar) a * b);
+    return (SkDScalar) ((SkDScalar) a * (SkDScalar) b);
 }
 
 static void computeOuterProduct(SkMatrix* matrix,