Add proper support for "use asm"; blocks. Disable -c optimization within "use asm"; sections and preserve floating point literals in their original form. Non-asm.js sections are optimized as before. Asm.js sections can still be mangled and minified of whitespace. No special command line flags are required.

lib/output.js

@@ -1158,7 +1158,11 @@ function OutputStream(options) {
         output.print_string(self.getValue(), self.quote);
     });
     DEFPRINT(AST_Number, function(self, output){
-        output.print(make_num(self.getValue()));
+        if (self.value_string !== undefined && self.scope && self.scope.has_directive('use asm')) {
+            output.print(self.value_string);
+        } else {
+            output.print(make_num(self.getValue()));
+        }
     });
 
     function regexp_safe_literal(code) {