fix a small oversight in request class

lowercase method name does not trigger type error properly (#362)

src/request.js

@@ -40,6 +40,7 @@ export default class Request {
 		}
 
 		let method = init.method || input.method || 'GET';
+		method = method.toUpperCase();
 
 		if ((init.body != null || input instanceof Request && input.body !== null) &&
 			(method === 'GET' || method === 'HEAD')) {
@@ -58,7 +59,7 @@ export default class Request {
 		});
 
 		// fetch spec options
-		this.method = method.toUpperCase();
+		this.method = method;
 		this.redirect = init.redirect || input.redirect || 'follow';
 		this.headers = new Headers(init.headers || input.headers || {});
 

test/test.js

@@ -1527,6 +1527,10 @@ describe('node-fetch', () => {
 			.to.throw(TypeError);
 		expect(() => new Request('.', { body: 'a', method: 'HEAD' }))
 			.to.throw(TypeError);
+		expect(() => new Request('.', { body: 'a', method: 'get' }))
+			.to.throw(TypeError);
+		expect(() => new Request('.', { body: 'a', method: 'head' }))
+			.to.throw(TypeError);
 	});
 
 	it('should support empty options in Response constructor', function() {