Handle symbols in FrameMirror#invocationText().

Fix a TypeError when putting together the invocationText for a symbol
method's stack frame.

See https://github.com/nodejs/node/issues/7536.

Review-Url: https://codereview.chromium.org/2122793003
Cr-Commit-Position: refs/heads/master@{#37597}

src/debug/mirrors.js

@@ -1499,6 +1499,12 @@ PropertyMirror.prototype.name = function() {
 };
 
 
+PropertyMirror.prototype.toText = function() {
+  if (IS_SYMBOL(this.name_)) return %SymbolDescriptiveString(this.name_);
+  return this.name_;
+};
+
+
 PropertyMirror.prototype.isIndexed = function() {
   for (var i = 0; i < this.name_.length; i++) {
     if (this.name_[i] < '0' || '9' < this.name_[i]) {
@@ -2034,10 +2040,10 @@ FrameMirror.prototype.invocationText = function() {
         if (display_receiver) {
           result += '.';
         }
-        result += property.name();
+        result += property.toText();
       } else {
         result += '[';
-        result += property.name();
+        result += property.toText();
         result += ']';
       }
       // Also known as - if the name in the function doesn't match the name

test/mjsunit/debug-backtrace-text.js

@@ -35,7 +35,8 @@ function Point(x, y) {
 
 Point.prototype.distanceTo = function(p) {
   debugger;
-  return Math.sqrt(Math.pow(Math.abs(this.x - p.x), 2) + Math.pow(Math.abs(this.y - p.y), 2))
+  return Math.sqrt(Math.pow(Math.abs(this.x - p.x), 2) +
+         Math.pow(Math.abs(this.y - p.y), 2))
 }
 
 p1 = new Point(1,1);
@@ -58,7 +59,7 @@ a=[1,2,distance];
 // Get the Debug object exposed from the debug context global object.
 Debug = debug.Debug
 
-testConstructor = false;  // Flag to control which part of the test is run.
+what = 'constructor';  // Flag to control which part of the test is run.
 listenerCalled = false;
 exception = false;
 
@@ -72,28 +73,45 @@ function safeEval(code) {
 
 function listener(event, exec_state, event_data, data) {
   try {
-  if (event == Debug.DebugEvent.Break)
+    if (event == Debug.DebugEvent.Break) {
-  {
+      if (what == 'constructor') {
-    if (!testConstructor) {
         // The expected backtrace is
-      // 0: Call distance on Point where distance is a property on the prototype
+        // 0: Call distance on Point where distance is a prototype property
         // 1: Call distance on Point where distance is a direct property
         // 2: Call on function an array element 2
         // 3: [anonymous]
-      assertEquals("#<Point>.distanceTo(p=#<Point>)", exec_state.frame(0).invocationText());
+        assertEquals("#<Point>.distanceTo(p=#<Point>)",
-      assertEquals("#<Point>.distanceTo(p=#<Point>)", exec_state.frame(1).invocationText());
+                     exec_state.frame(0).invocationText());
-      assertEquals("#<Array>[2](aka distance)(p=#<Point>, q=#<Point>)", exec_state.frame(2).invocationText());
+        assertEquals("#<Point>.distanceTo(p=#<Point>)",
+                     exec_state.frame(1).invocationText());
+        assertEquals("#<Array>[2](aka distance)(p=#<Point>, q=#<Point>)",
+                     exec_state.frame(2).invocationText());
         assertEquals("[anonymous]()", exec_state.frame(3).invocationText());
         listenerCalled = true;
-    } else {
+      } else if (what == 'breakpoint') {
         // The expected backtrace is
         // 0: Call Point constructor
         // 1: Call on global function createPoint
         // 2: [anonymous]
-      assertEquals("new Point(x=0, y=0)", exec_state.frame(0).invocationText());
+        assertEquals("new Point(x=0, y=0)",
-      assertEquals("createPoint(x=0, y=0)", exec_state.frame(1).invocationText());
+                     exec_state.frame(0).invocationText());
+        assertEquals("createPoint(x=0, y=0)",
+                     exec_state.frame(1).invocationText());
         assertEquals("[anonymous]()", exec_state.frame(2).invocationText());
         listenerCalled = true;
+      } else if (what == 'symbol') {
+        // The expected backtrace is
+        // 0: Call Point constructor
+        // 1: Call on symbol method
+        // 2: [anonymous]
+        assertEquals("new Point(x=0, y=0)",
+                     exec_state.frame(0).invocationText());
+        assertEquals("#<Object>[Symbol(Das Symbol)](x=0, y=0)",
+                     exec_state.frame(1).invocationText());
+        assertEquals("[anonymous]()", exec_state.frame(2).invocationText());
+        listenerCalled = true;
+      } else {
+        assertUnreachable();
       }
     }
   } catch (e) {
@@ -112,11 +130,21 @@ assertTrue(listenerCalled);
 assertFalse(exception, "exception in listener")
 
 // Set a break point and call to invoke the debug event listener.
+what = 'breakpoint';
 listenerCalled = false;
-testConstructor = true;
 Debug.setBreakPoint(Point, 0, 0);
 createPoint(0, 0);
 
 // Make sure that the debug event listener vas invoked (again).
 assertTrue(listenerCalled);
 assertFalse(exception, "exception in listener")
+
+what = 'symbol';
+listenerCalled = false;
+var S = Symbol('Das Symbol');
+var o = { [S](x, y) { return new Point(x, y); } };
+Debug.setBreakPoint(Point, 0, 0);
+o[S](0, 0);
+
+assertTrue(listenerCalled);
+assertFalse(exception, "exception in listener")