Adds descriptor properties to a candidate, pushes to the candidates array
@return undefined
 (Declared outside of the while loop so that it's only created once. (This fn is defined before it is used, in order to pass JSHINT. Unfortunately this breaks the sequencing of the spec comments. :/ )
function parseDescriptors() {

			// 9. Descriptor parser: Let error be no.
			var pError = false,

			// 10. Let width be absent.
			// 11. Let density be absent.
			// 12. Let future-compat-h be absent. (We're implementing it now as h)
			    w, d, h, i,
			    candidate = {},
			    desc, lastChar, value, intVal, floatVal;

			// 13. For each descriptor in descriptors, run the appropriate set of steps
			// from the following list:
			for (i = 0 ; i < descriptors.length; i++) {
				desc = descriptors[ i ];

				lastChar = desc[ desc.length - 1 ];
				value = desc.substring(0, desc.length - 1);
				intVal = parseInt(value, 10);
				floatVal = parseFloat(value);

				// If the descriptor consists of a valid non-negative integer followed by
				// a U+0077 LATIN SMALL LETTER W character
				if (regexNonNegativeInteger.test(value) && (lastChar === "w")) {

					// If width and density are not both absent, then let error be yes.
					if (w || d) {pError = true;}

					// Apply the rules for parsing non-negative integers to the descriptor.
					// If the result is zero, let error be yes.
					// Otherwise, let width be the result.
					if (intVal === 0) {pError = true;} else {w = intVal;}

				// If the descriptor consists of a valid floating-point number followed by
				// a U+0078 LATIN SMALL LETTER X character
				} else if (regexFloatingPoint.test(value) && (lastChar === "x")) {

					// If width, density and future-compat-h are not all absent, then let error
					// be yes.
					if (w || d || h) {pError = true;}

					// Apply the rules for parsing floating-point number values to the descriptor.
					// If the result is less than zero, let error be yes. Otherwise, let density
					// be the result.
					if (floatVal < 0) {pError = true;} else {d = floatVal;}

				// If the descriptor consists of a valid non-negative integer followed by
				// a U+0068 LATIN SMALL LETTER H character
				} else if (regexNonNegativeInteger.test(value) && (lastChar === "h")) {

					// If height and density are not both absent, then let error be yes.
					if (h || d) {pError = true;}

					// Apply the rules for parsing non-negative integers to the descriptor.
					// If the result is zero, let error be yes. Otherwise, let future-compat-h
					// be the result.
					if (intVal === 0) {pError = true;} else {h = intVal;}

				// Anything else, Let error be yes.
				} else {pError = true;}
			} // (close step 13 for loop)

			// 15. If error is still no, then append a new image source to candidates whose
			// URL is url, associated with a width width if not absent and a pixel
			// density density if not absent. Otherwise, there is a parse error.
			if (!pError) {
				candidate.url = url;

				if (w) { candidate.w = w;}
				if (d) { candidate.d = d;}
				if (h) { candidate.h = h;}
				if (!h && !d && !w) {candidate.d = 1;}
				if (candidate.d === 1) {set.has1x = true;}
				candidate.set = set;

				candidates.push(candidate);
			}
		}