[tools] Add file positions to map-explorer

NOTRY=true

Change-Id: I076e2f6c39674a98827e5939c9527678a5f81368
Reviewed-on: https://chromium-review.googlesource.com/c/1354882
Commit-Queue: Marja Hölttä <marja@chromium.org>
Reviewed-by: Camillo Bruni <cbruni@chromium.org>
Cr-Commit-Position: refs/heads/master@{#57931}

tools/map-processor.html

@@ -665,6 +665,7 @@ class View {
     let details = "";
     if (this.map) {
       details += "ID: " + this.map.id;
+      details += "\nSource location: " + this.map.filePosition;
       details += "\n" + this.map.description;
     }
     $("mapDetails").innerText = details;

tools/map-processor.js

@@ -151,7 +151,7 @@ class MapProcessor extends LogReader {
     from = this.getExistingMap(from, time);
     to = this.getExistingMap(to, time);
     let edge = new Edge(type, name, reason, time, from, to);
-    edge.filePosition = this.formatPC(pc, line, column);
+    to.filePosition = this.formatPC(pc, line, column);
     edge.finishSetup();
   }
 
@@ -209,6 +209,7 @@ class V8Map {
     V8Map.set(id, this);
     this.leftId = 0;
     this.rightId = 0;
+    this.filePosition = "";
   }
 
   finalize(id) {
@@ -319,7 +320,6 @@ class Edge {
     this.time = time;
     this.from = from;
     this.to = to;
-    this.filePosition = "";
   }
 
   finishSetup() {