Array length reduction should throw in strict mode if it can't delete an element.

src/objects-printer.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/objects.h"
 
 #include "src/disasm.h"
 #include "src/disassembler.h"
 #include "src/interpreter/bytecodes.h"
 #include "src/objects-inl.h"
@@ skipping 353 matching lines @@
     PRINT_ELEMENTS(UINT16_ELEMENTS, FixedUint16Array)
     PRINT_ELEMENTS(INT16_ELEMENTS, FixedInt16Array)
     PRINT_ELEMENTS(UINT32_ELEMENTS, FixedUint32Array)
     PRINT_ELEMENTS(INT32_ELEMENTS, FixedInt32Array)
     PRINT_ELEMENTS(FLOAT32_ELEMENTS, FixedFloat32Array)
     PRINT_ELEMENTS(FLOAT64_ELEMENTS, FixedFloat64Array)
 
 #undef PRINT_ELEMENTS
 
     case DICTIONARY_ELEMENTS:
+      os << "\n - elements: ";
       elements()->Print(os);
       break;
     case FAST_SLOPPY_ARGUMENTS_ELEMENTS:
     case SLOW_SLOPPY_ARGUMENTS_ELEMENTS: {
       FixedArray* p = FixedArray::cast(elements());
       os << "\n   parameter map:";
       for (int i = 2; i < p->length(); i++) {
         os << " " << (i - 2) << ":" << Brief(p->get(i));
       }
       os << "\n   context: " << Brief(p->get(0))
@@ skipping 937 matching lines @@
 void JSObject::PrintTransitions(std::ostream& os) {  // NOLINT
   Object* transitions = map()->raw_transitions();
   int num_transitions = TransitionArray::NumberOfTransitions(transitions);
   if (num_transitions == 0) return;
   os << "\n - transitions";
   TransitionArray::PrintTransitions(os, transitions, false);
 }
 #endif  // defined(DEBUG) || defined(OBJECT_PRINT)
 }  // namespace internal
 }  // namespace v8