[turbolizer] Improve effect/control chain exploration

Shortcuts e and c select (and make visible) the next effect/control
node downwards in the chain; ALT+e/c moves upward.

Additionally, the graph bounding box is redetermined every time the
graph is redrawn (instead of only when relayouted).

Bug: v8:7327
Change-Id: If01b16fc25273703e25e429bdc36753a2fa87f7c
Reviewed-on: https://chromium-review.googlesource.com/1064210
Commit-Queue: Sigurd Schneider <sigurds@chromium.org>
Reviewed-by: Tobias Tebbi <tebbi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#53259}

tools/turbolizer/graph-layout.js

@@ -489,5 +489,4 @@ function redetermineGraphBoundingBox(graph) {
 
   graph.maxGraphX = graph.maxGraphNodeX +
     graph.maxBackEdgeNumber * MINIMUM_EDGE_SEPARATION;
-
 }

tools/turbolizer/graph-view.js

@@ -540,7 +540,7 @@ class GraphView extends View {
 
     var showSelectionFrontierNodes = function (inEdges, filter, select) {
       var frontier = graph.getNodeFrontier(state.selection, inEdges, filter);
-      if (frontier != undefined) {
+      if (frontier != undefined && frontier.size) {
         if (select) {
           if (!d3.event.shiftKey) {
             state.selection.clear();
@@ -585,13 +585,13 @@ class GraphView extends View {
         break;
       case 67:
         // 'c'
-        showSelectionFrontierNodes(!d3.event.altKey,
+        showSelectionFrontierNodes(d3.event.altKey,
           (edge, index) => { return edge.type == 'control'; },
           true);
         break;
       case 69:
         // 'e'
-        showSelectionFrontierNodes(!d3.event.altKey,
+        showSelectionFrontierNodes(d3.event.altKey,
             (edge, index) => { return edge.type == 'effect'; },
             true);
         break;
@@ -892,6 +892,7 @@ class GraphView extends View {
     });
 
     graph.svg.style.height = '100%';
+    redetermineGraphBoundingBox(this);
   }
 
   getVisibleTranslation(translate, scale) {