Fix state restoration when the number of scrollback lines is less than session height.

sources/VT100Screen.m

@@ -4826,7 +4826,7 @@ static void SwapInt(int *a, int *b) {
     if (includeRestorationBanner && [iTermAdvancedSettingsModel showSessionRestoredBanner]) {
         [lineBuffer appendMessage:@"Session Contents Restored"];
     }
-    [lineBuffer setMaxLines:maxScrollbackLines_];
+    [lineBuffer setMaxLines:maxScrollbackLines_ + self.height];
     if (!unlimitedScrollback_) {
         [lineBuffer dropExcessLinesWithWidth:self.width];
     }
@@ -4848,6 +4848,12 @@ static void SwapInt(int *a, int *b) {
     currentGrid_.cursorY = linesRestored + 1;
     currentGrid_.cursorX = 0;
+    // Reduce line buffer's max size to not include the grid height. This is its final state.
+    [lineBuffer setMaxLines:maxScrollbackLines_];
+    if (!unlimitedScrollback_) {
+        [lineBuffer dropExcessLinesWithWidth:self.width];
+    }
+
     if (screenState) {
         [tabStops_ removeAllObjects];
         [tabStops_ addObjectsFromArray:screenState[kScreenStateTabStopsKey]];