Fix for issue 14790 - Crash when using dartium devtools

runtime/vm/stack_frame_ia32.h

Index: runtime/vm/stack_frame_ia32.h
===================================================================
--- runtime/vm/stack_frame_ia32.h	(revision 30084)
+++ runtime/vm/stack_frame_ia32.h	(working copy)
@@ -14,18 +14,23 @@
                | saved EBP          |    (EBP of current frame)
                | saved PC           |    (PC of current frame)
                +--------------------+
-Current frame  | ...                | <- ESP of current frame
-               | first local        |
+Current frame  | ...               T| <- ESP of current frame
+               | first local       T|
                | PC marker          |    (current frame's code entry + offset)
                | caller's EBP       | <- EBP of current frame
                | caller's ret addr  |    (PC of caller frame)
                +--------------------+
 Caller frame   | last parameter     | <- ESP of caller frame
                |  ...               |
+
+               T against a slot indicates it needs to be traversed during GC.
 */
 
 static const int kDartFrameFixedSize = 3;  // PC marker, EBP, PC.
 static const int kSavedPcSlotFromSp = -1;
+
+static const int kFirstObjectSlotFromFp = -2;  // Used by GC to traverse stack.
+
 static const int kFirstLocalSlotFromFp = -2;
 static const int kPcMarkerSlotFromFp = -1;
 static const int kSavedCallerFpSlotFromFp = 0;
@@ -43,4 +48,3 @@
 }  // namespace dart
 
 #endif  // VM_STACK_FRAME_IA32_H_
-