Use the statically-inferred name for anonymous functions (bug 786711) r=msucan,vporof

browser/devtools/debugger/test/browser_dbg_displayName.html

@@ -14,8 +14,11 @@ var a = function() {
 var anon = a();
 anon.displayName = "anonFunc";
 
+var inferred = a();
+
 function evalCall() {
   eval("anon();");
+  eval("inferred();");
 }
 
 </script>

browser/devtools/debugger/test/browser_dbg_displayName.js

@@ -3,6 +3,9 @@
  * http://creativecommons.org/publicdomain/zero/1.0/
  */
 
+// Tests that anonymous functions appear in the stack frame list with either
+// their displayName property or a SpiderMonkey-inferred name.
+
 var gPane = null;
 var gTab = null;
 var gDebuggee = null;
@@ -36,13 +39,35 @@ function testAnonCall() {
       is(frames.querySelector("#stackframe-0 .dbg-stackframe-name").getAttribute("value"),
         "anonFunc", "Frame name should be anonFunc");
 
-      resumeAndFinish();
+      testInferredName();
     }}, 0);
   });
 
   gDebuggee.evalCall();
 }
 
+function testInferredName() {
+  gDebugger.DebuggerController.activeThread.addOneTimeListener("framesadded", function() {
+    Services.tm.currentThread.dispatch({ run: function() {
+
+      let frames = gDebugger.DebuggerView.StackFrames._frames;
+
+      is(gDebugger.DebuggerController.activeThread.state, "paused",
+        "Should only be getting stack frames while paused.");
+
+      is(frames.querySelectorAll(".dbg-stackframe").length, 3,
+        "Should have three frames.");
+
+      is(frames.querySelector("#stackframe-0 .dbg-stackframe-name").getAttribute("value"),
+        "a/<", "Frame name should be a/<");
+
+      resumeAndFinish();
+    }}, 0);
+  });
+
+  gDebugger.DebuggerController.activeThread.resume();
+}
+
 function resumeAndFinish() {
   gDebugger.DebuggerController.activeThread.resume(function() {
     removeTab(gTab);

toolkit/devtools/debugger/server/dbg-script-actors.js

@@ -1821,9 +1821,14 @@ function getFunctionName(aFunction) {
   if (aFunction.name) {
     name = aFunction.name;
   } else {
+    // Check if the developer has added a de-facto standard displayName
+    // property for us to use.
     let desc = aFunction.getOwnPropertyDescriptor("displayName");
     if (desc && desc.value && typeof desc.value == "string") {
       name = desc.value;
+    } else if ("displayName" in aFunction) {
+      // Otherwise use SpiderMonkey's inferred name.
+      name = aFunction.displayName;
     }
   }
   return name;