Fix crashes during GC caused by partially initialized objects. The...

src/x64/stub-cache-x64.cc

Index: src/x64/stub-cache-x64.cc
===================================================================
--- src/x64/stub-cache-x64.cc	(revision 5878)
+++ src/x64/stub-cache-x64.cc	(working copy)
@@ -2890,8 +2890,7 @@
 
 // Specialized stub for constructing objects from functions which only have only
 // simple assignments of the form this.x = ...; in their body.
-MaybeObject* ConstructStubCompiler::CompileConstructStub(
-    SharedFunctionInfo* shared) {
+MaybeObject* ConstructStubCompiler::CompileConstructStub(JSFunction* function) {
   // ----------- S t a t e -------------
   //  -- rax : argc
   //  -- rdi : constructor
@@ -2964,6 +2963,7 @@
   // r9: first in-object property of the JSObject
   // Fill the initialized properties with a constant value or a passed argument
   // depending on the this.x = ...; assignment in the function.
+  SharedFunctionInfo* shared = function->shared();
   for (int i = 0; i < shared->this_property_assignments_count(); i++) {
     if (shared->IsThisPropertyAssignmentArgument(i)) {
       // Check if the argument assigned to the property is actually passed.
@@ -2983,8 +2983,9 @@
   }
 
   // Fill the unused in-object property fields with undefined.
+  ASSERT(function->has_initial_map());
   for (int i = shared->this_property_assignments_count();
-       i < shared->CalculateInObjectProperties();
+       i < function->initial_map()->inobject_properties();
        i++) {
     __ movq(Operand(r9, i * kPointerSize), r8);
   }