Throw warning for unsupported runtimes, e.g. Node < 6 (#4839)

Author: GeoffreyBooth

bin/cake

@@ -1,5 +1,12 @@
 #!/usr/bin/env node
 
+try {
+  new Function('var {a} = {a: 1}')();
+} catch (error) {
+  console.error('Your JavaScript runtime does not support some features used by the cake command. Please use Node 6 or later.');
+  process.exit(1);
+}
+
 var path = require('path');
 var fs   = require('fs');
 

bin/coffee

@@ -1,5 +1,12 @@
 #!/usr/bin/env node
 
+try {
+  new Function('var {a} = {a: 1}')();
+} catch (error) {
+  console.error('Your JavaScript runtime does not support some features used by the coffee command. Please use Node 6 or later.');
+  process.exit(1);
+}
+
 var path = require('path');
 var fs   = require('fs');