Clip scroll margins to reasonable values

FIX: Fix an issue where passing large scroll margins to `scrollIntoView` would
cause the measure loop to fail to terminate.

src/docview.ts

@@ -514,8 +514,11 @@ export class DocView extends ContentView {
       left: rect.left - margins.left, top: rect.top - margins.top,
       right: rect.right + margins.right, bottom: rect.bottom + margins.bottom
     }
+    let sDOM = this.view.scrollDOM
     scrollRectIntoView(this.view.scrollDOM, targetRect, range.head < range.anchor ? -1 : 1,
-                       target.x, target.y, target.xMargin, target.yMargin,
+                       target.x, target.y,
+                       Math.max(0, Math.min(target.xMargin, sDOM.offsetWidth)),
+                       Math.max(0, Math.min(target.yMargin, sDOM.offsetHeight)),
                        this.view.textDirection == Direction.LTR)
   }
 

src/editorview.ts

@@ -843,9 +843,11 @@ export class EditorView {
     x?: ScrollStrategy,
     /// Extra vertical distance to add when moving something into
     /// view. Not used with the `"center"` strategy. Defaults to 5.
+    /// Must be less than the height of the editor.
     yMargin?: number,
     /// Extra horizontal distance to add. Not used with the `"center"`
-    /// strategy. Defaults to 5.
+    /// strategy. Defaults to 5. Must be less than the width of the
+    /// editor.
     xMargin?: number,
   } = {}): StateEffect<unknown> {
     return scrollIntoView.of(new ScrollTarget(typeof pos == "number" ? EditorSelection.cursor(pos) : pos,