Non-functional. Rationalizations enabling future generalizations:

- Use much simpler method to update implicit array sizes.
  The previous overly complicated method was error prone.
- Rationalize all use of unsized arrays.
- Combine decorations when generating SPIR-V, to simplify
  adding extensions.

SPIRV/SpvBuilder.cpp

@@ -854,9 +854,9 @@ Id Builder::makeFpConstant(Id type, double d, bool specConstant)
 
         switch (getScalarTypeWidth(type)) {
         case 16:
-                return makeFloat16Constant(d, specConstant);
+                return makeFloat16Constant((float)d, specConstant);
         case 32:
-                return makeFloatConstant(d, specConstant);
+                return makeFloatConstant((float)d, specConstant);
         case 64:
                 return makeDoubleConstant(d, specConstant);
         default: