Fix handling of oblique fonts

Take font weight into account when measuring text width.

Note that there will still be some issues with certain fonts due to
overlapping transparent billboards. That will be fixed with #2130.

Fixes #3782

Source/ThirdParty/measureText.js

@@ -95,14 +95,16 @@ define(function() {
     var metrics = context2D.measureText(textstring),
         fontFamily = getCSSValue(context2D.canvas,"font-family"),
         fontSize = getCSSValue(context2D.canvas,"font-size").replace("px",""),
+        fontStyle = getCSSValue(context2D.canvas,"font-style"),
+        fontWeight = getCSSValue(context2D.canvas,"font-weight"),
         isSpace = !(/\S/.test(textstring));
         metrics.fontsize = fontSize;
 
     // for text lead values, we meaure a multiline text container.
     var leadDiv = document.createElement("div");
     leadDiv.style.position = "absolute";
     leadDiv.style.opacity = 0;
-    leadDiv.style.font = fontSize + "px " + fontFamily;
+    leadDiv.style.font = fontStyle + " " + fontWeight + " " + fontSize + "px " + fontFamily;
     leadDiv.innerHTML = textstring + "<br/>" + textstring;
     document.body.appendChild(leadDiv);
 
@@ -125,8 +127,10 @@ define(function() {
         canvas.style.opacity = 1;
         canvas.style.fontFamily = fontFamily;
         canvas.style.fontSize = fontSize;
+        canvas.style.fontStyle = fontStyle;
+        canvas.style.fontWeight = fontWeight;
         var ctx = canvas.getContext("2d");
-        ctx.font = fontSize + "px " + fontFamily;
+        ctx.font = fontStyle + " " + fontWeight + " " + fontSize + "px " + fontFamily;
 
         var w = canvas.width,
             h = canvas.height,