Make "three snapshot technique" work on heap snapshots loaded from files

LayoutTests/inspector-protocol/cpu-profiler/record-cpu-profile.html

Index: LayoutTests/inspector-protocol/cpu-profiler/record-cpu-profile.html
diff --git a/LayoutTests/inspector-protocol/cpu-profiler/record-cpu-profile.html b/LayoutTests/inspector-protocol/cpu-profiler/record-cpu-profile.html
index 6f97a3c79f678703bc9ab57bfd49f02162033afe..f9d9c9e0493ca9df91b124ad3f00f1c848d699ca 100644
--- a/LayoutTests/inspector-protocol/cpu-profiler/record-cpu-profile.html
+++ b/LayoutTests/inspector-protocol/cpu-profiler/record-cpu-profile.html
@@ -14,14 +14,14 @@ function test()
     {
         if (!InspectorTest.expectedSuccess("startFrontendProfile", messageObject))
             return;
-        InspectorTest.sendCommand("Runtime.evaluate", {expression: "console.profile('org.webkit.profiles.user-initiated.1');"}, didStartConsoleProfile);
+        InspectorTest.sendCommand("Runtime.evaluate", {expression: "console.profile('Profile 1');"}, didStartConsoleProfile);
     }
 
     function didStartConsoleProfile(messageObject)
     {
         if (!InspectorTest.expectedSuccess("startConsoleProfile", messageObject))
             return;
-        InspectorTest.sendCommand("Runtime.evaluate", {expression: "console.profileEnd('org.webkit.profiles.user-initiated.1');"}, didStopConsoleProfile);
+        InspectorTest.sendCommand("Runtime.evaluate", {expression: "console.profileEnd('Profile 1');"}, didStopConsoleProfile);
     }
 
     function didStopConsoleProfile(messageObject)