hterm: start implementing findbar searching

Searching is done in batch size of 50 rows and other batches are
scheduled asynchronously to avoid blocking of UI-thread and screen
freezing.

Change-Id: I5115d8f92013511171002f3e71d42150338b386e
Reviewed-on: https://chromium-review.googlesource.com/c/apps/libapps/+/2290488
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Jason Lin <lxj@google.com>
Reviewed-by: Joel Hockey <joelhockey@chromium.org>
diff --git a/hterm/js/hterm_terminal.js b/hterm/js/hterm_terminal.js
index 548e6f6..fca1f12 100644
--- a/hterm/js/hterm_terminal.js
+++ b/hterm/js/hterm_terminal.js
@@ -953,6 +953,13 @@
 };
 
 /**
+ * @return {!hterm.ScrollPort}
+ */
+hterm.Terminal.prototype.getScrollPort = function() {
+  return this.scrollPort_;
+};
+
+/**
  * Update CSS character size variables to match the scrollport.
  */
 hterm.Terminal.prototype.updateCssCharsize_ = function() {