title: Why echarts are not showing on I.E-11 version
body: <p>I had created a project using vuejs+Vue-CLI and integrated echarts in it. Echarts are working well in all browsers but when I open it in IE-11 version, page can't load and it shows following error: </p>
  
  <blockquote>
    <p>[object Error]{description: "Expected ')'", message: "Expected ')'", name: "SyntaxError", number: -2146827282, stack: "SyntaxError...", Symbol()_n.kyufm4c0tec: undefined, Symbol()_p.kyufm4c0tec: undefined, Symbol()_q.kyufm4c0tec: undefined, Symbol()_r.kyufm4c0tec: undefined, Symbol(Lang fallback)_m.kyufm4c0tec: undefined, Symbol(util.promisify.custom)_o.kyufm4c0tec: undefined} </p>
  </blockquote>
  
  <p>Here is my code: </p>
  
  <pre><code>&lt;template&gt;
      &lt;ECharts :options="pie" style="width:300px; height:260px"&gt;
      &lt;/ECharts&gt;
  &lt;/template&gt;
  
  &lt;script&gt;
      import ECharts from "vue-echarts/components/ECharts.vue";
      import "echarts/lib/chart/pie";
      import "echarts/lib/component/title";
  
      export default {
          components: {
              ECharts
          },
          data() {
              return {
                  pie: {
                      backgroundColor: "transparent",
                      tooltip: {
                          trigger: "item",
                          formatter: "{a} &lt;br/&gt;{b} : {c} ({d}%)"
                      },
                      series: [{
                          name: "Product Sales",
                          type: "pie",
                          radius: ["50%", "70%"],
                          avoidLabelOverlap: false,
                          data: [{
                                  value: 1,
                                  name: "Product A"
                              },
                              {
                                  value: 2,
                                  name: "Product B"
                              },
                              {
                                  value: 3,
                                  name: "Product C"
                              }
                          ],
                          label: {
                              normal: {
                                  show: false,
                                  position: "center"
                              },
                              emphasis: {
                                  show: true,
                                  textStyle: {
                                      fontSize: "20",
                                      fontWeight: "bold"
                                  }
                              }
                          },
                          labelLine: {
                              normal: {
                                  show: false
                              }
                          }
                      }]
                  }
              };
          }
      };
  &lt;/script&gt;
  </code></pre>
  
  <p>what's an issue in IE browser I also searched for the solution and tried it but did't get the result. 
  Versions:</p>
  
  <blockquote>
    <p>echarts-4.1.0,
    vue-echarts: 3.1.1</p>
  </blockquote>
  
  <p>Any help will be appreciated! Thanks</p>