Base wrapped line on current width, not original width

Lines are never trimmed, so even if the term's size is reduced it
could contain empty lines at the end when wrapping is valid

src/addons/winptyCompat/winptyCompat.ts

@@ -43,7 +43,7 @@ declare var define: any;
     // wrapped.
     this.on('lineFeed', () => {
       const line = this.buffer.lines.get(this.buffer.ybase + this.buffer.y - 1);
-      const lastChar = line[line.length - 1];
+      const lastChar = line[this.cols - 1];
       if (lastChar[3] !== 32 /* ' ' */) {
         const nextLine = this.buffer.lines.get(this.buffer.ybase + this.buffer.y);
         (<any>nextLine).isWrapped = true;