应用js获取不到svg标签的宽高

使用js获取不到svg标签的宽高
RT：
html代码为：

<!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.1//EN" "http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd">

<svg version="1.1" id="one" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" x="0px" y="0px"

	 width="601px" height="492px" viewBox="-5.86 4.5 601 492" enable-background="new -5.86 4.5 601 492" xml:space="preserve">

<polygon id="test" onclick="addflag(this)" fill="#FFFCD1" points="491.408,204.173 491.408,204.173 491.185,203.726 

	491.882,202.082 492.802,201.382 493.5,200.686 494.672,199.765 495.817,197.449 495.817,195.58 493.279,194.185 493.028,192.791 

	493.028,191.646 493.279,190.698 493.724,189.776 494.895,188.16 496.513,186.764 496.989,185.815 497.434,184.895 497.685,182.802 

	497.685,181.184 497.685,179.539 493.279,174.656 491.185,174.433 487.223,175.13 485.606,176.525 484.209,178.144 481.198,181.63 

	479.104,185.119 477.933,186.764 476.761,188.16 472.129,185.119 470.038,183.5 468.168,182.105 466.55,181.882 465.378,181.407 

	464.682,180.71 463.985,180.235 463.985,178.617 464.236,177.697 464.458,177.446 464.682,177.222 466.077,177 467.249,175.354 

	468.643,173.735 468.418,167.682 467.946,167.458 467.249,166.287 466.327,163.748 466.327,161.404 466.55,160.483 467.025,159.787 

	467.946,160.261 468.643,160.707 469.117,161.878 469.563,163.273 470.736,164.194 471.907,165.143 472.604,165.589 

	473.301,165.839 474.222,165.839 475.617,165.589 477.709,163.498 480.5,161.404 483.513,159.089 486.302,156.773 489.092,154.681 

	490.237,153.287 490.934,151.891 492.329,149.324 494.421,148.626 496.291,148.152 496.989,148.152 497.909,148.403 499.08,148.851 

	500.225,149.548 502.568,149.548 504.41,147.455 504.41,141.652 505.108,139.783 506.054,140.034 507.45,140.731 508.593,141.876 

	509.99,143.522 511.384,144.666 512.555,145.139 514.173,145.363 514.649,144.917 514.871,143.968 515.093,143.046 516.265,141.652 

	517.185,142.573 517.438,147.009 518.832,148.626 520.199,150.496 521.845,152.587 523.938,154.681 523.938,160.483 

	525.554,162.576 529.517,165.366 532.28,167.235 532.054,167.933 531.359,168.853 528.822,170.723 526.031,172.564 524.383,173.735 

	522.291,175.828 520.451,177.919 518.832,180.013 518.58,180.933 518.359,182.105 518.135,183.277 517.662,184.419 516.042,185.119 

	514.173,186.066 511.859,186.513 509.765,187.21 507.898,188.16 506.054,189.08 504.41,190.251 503.014,191.646 501.397,193.264 

	500,195.132 499.304,197.226 498.382,199.988 497.685,202.778 494.199,203.726 "/>

<polygon id="test1" onclick="addflag(this)" fill="#FFFCD1" points="532.334,165.785 532.334,165.785 530.941,164.389 

	529.072,162.996 526.057,161.153 525.136,159.982 525.362,156.271 525.136,154.876 524.663,153.481 523.491,152.31 522.794,151.612 

	522.096,150.216 518.86,146.73 518.61,146.507 518.385,141.848 517.464,140.927 516.768,140.453 516.071,140.453 515.372,140.453 

	514.675,141.402 514.202,142.099 513.281,144.191 512.805,144.191 509.792,141.15 508.399,139.755 507.003,138.835 504.911,138.36 

	503.516,137.914 502.344,137.439 501.647,136.52 500.95,135.821 500.726,134.65 500.029,131.86 499.331,130.019 498.16,128.373