fix: this.outro need to be mapped (#300)

Author: hai-x

src/MagicString.js

@@ -168,6 +168,10 @@ export default class MagicString {
 			if (chunk.outro.length) mappings.advance(chunk.outro);
 		});
 
+		if (this.outro) {
+			mappings.advance(this.outro);
+		}
+
 		return {
 			file: options.file ? options.file.split(/[/\\]/).pop() : undefined,
 			sources: [

test/MagicString.test.js

@@ -279,6 +279,19 @@ describe('MagicString', () => {
 			assert.equal(originLoc.column, 0);
 		});
 
+		it('should generate a correct sourcemap including correct lines', () => {
+			const s = new MagicString(
+				'var answer = 42;\nconsole.log("the answer is %s", answer);'
+			);
+			s.append('\n\n\n\n}).call(global);');
+			assert.equal(
+				// output lines
+				s.toString().split('\n').length,
+				// sourcemap lines
+				s.generateDecodedMap().mappings.length
+			);
+		});
+
 		it('should generate a sourcemap using specified locations', () => {
 			const s = new MagicString('abcdefghijkl');