Chrome 48 supports classes in strict mode

That's just the same as Node 4 and 5. However, we only emit strict code and
parse everything as strict code. Closes #66.

src/support.js

@@ -1,6 +1,6 @@
 export const matrix = {
 	chrome: {
-		    48: 0b01001010100011001101,
+		    48: 0b01001010100011001111,
 		    49: 0b01001111100111111111,
 		    50: 0b01011111100111111111,
 		    51: 0b01011111100111111111,