Allow a line handle to be passed to heightAtLine

Author: marijnh

doc/manual.html

@@ -1811,7 +1811,7 @@ <h3 id="api_sizing">Sizing, scrolling and positioning methods</h3>
       height. <code>mode</code> can be one of the same strings
       that <a href="#coordsChar"><code>coordsChar</code></a>
       accepts.</dd>
-      <dt id="heightAtLine"><code><strong>cm.heightAtLine</strong>(line: number, ?mode: string) → number</code></dt>
+      <dt id="heightAtLine"><code><strong>cm.heightAtLine</strong>(line: integer|LineHandle, ?mode: string) → number</code></dt>
       <dd>Computes the height of the top of a line, in the coordinate
       system specified by <code>mode</code>
       (see <a href="#coordsChar"><code>coordsChar</code></a>), which

lib/codemirror.js

@@ -4929,10 +4929,15 @@
       return lineAtHeight(this.doc, height + this.display.viewOffset);
     },
     heightAtLine: function(line, mode) {
-      var end = false, last = this.doc.first + this.doc.size - 1;
-      if (line < this.doc.first) line = this.doc.first;
-      else if (line > last) { line = last; end = true; }
-      var lineObj = getLine(this.doc, line);
+      var end = false, lineObj;
+      if (typeof line == "number") {
+        var last = this.doc.first + this.doc.size - 1;
+        if (line < this.doc.first) line = this.doc.first;
+        else if (line > last) { line = last; end = true; }
+        lineObj = getLine(this.doc, line);
+      } else {
+        lineObj = line;
+      }
       return intoCoordSystem(this, lineObj, {top: 0, left: 0}, mode || "page").top +
         (end ? this.doc.height - heightAtLine(lineObj) : 0);
     },