Avoid ASSERT_NOT_REACHED in blink::floatValueForLength.

Source/core/svg/SVGLengthContext.cpp

Index: Source/core/svg/SVGLengthContext.cpp
diff --git a/Source/core/svg/SVGLengthContext.cpp b/Source/core/svg/SVGLengthContext.cpp
index 22c7d580dce1f7b6ad11b329d4f800c804024fa3..cbbbc4ccb11222e305bf87f1fab896dd11c8c648 100644
--- a/Source/core/svg/SVGLengthContext.cpp
+++ b/Source/core/svg/SVGLengthContext.cpp
@@ -176,6 +176,10 @@ float SVGLengthContext::valueForLength(const Length& length, const ComputedStyle
 float SVGLengthContext::valueForLength(const Length& length, float zoom, float dimension)
 {
     ASSERT(zoom != 0);
+    // isIntrinsic can occur for 'width' and 'height', but has no
+    // real meaning for svg.
+    if (length.isIntrinsic())
+        return 0;
     return floatValueForLength(length, dimension * zoom) / zoom;
 }