[proxy] fixing harmony/proxy.js tests and improving error messages + some drive-by fixes

src/full-codegen/ppc/full-codegen-ppc.cc

 // Copyright 2014 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.
 
 #if V8_TARGET_ARCH_PPC
 
 #include "src/ast/scopes.h"
 #include "src/code-factory.h"
 #include "src/code-stubs.h"
 #include "src/codegen.h"
@@ skipping 1089 matching lines @@
   __ LoadP(r5, MemOperand(sp, 3 * kPointerSize));
 
   // Check if the expected map still matches that of the enumerable.
   // If not, we may have to filter the key.
   Label update_each;
   __ LoadP(r4, MemOperand(sp, 4 * kPointerSize));
   __ LoadP(r7, FieldMemOperand(r4, HeapObject::kMapOffset));
   __ cmp(r7, r5);
   __ beq(&update_each);
 
-  // For proxies, no filtering is done.
-  // TODO(rossberg): What if only a prototype is a proxy? Not specified yet.
-  __ CmpSmiLiteral(r5, Smi::FromInt(0), r0);
-  __ beq(&update_each);
-
   // Convert the entry to a string or (smi) 0 if it isn't a property
   // any more. If the property has been removed while iterating, we
   // just skip it.
   __ Push(r4, r6);  // Enumerable and current entry.
   __ CallRuntime(Runtime::kForInFilter, 2);
   PrepareForBailoutForId(stmt->FilterId(), TOS_REG);
   __ mr(r6, r3);
   __ LoadRoot(r0, Heap::kUndefinedValueRootIndex);
   __ cmp(r3, r0);
   __ beq(loop_statement.continue_label());
@@ skipping 3774 matching lines @@
     return ON_STACK_REPLACEMENT;
   }
 
   DCHECK(interrupt_address ==
          isolate->builtins()->OsrAfterStackCheck()->entry());
   return OSR_AFTER_STACK_CHECK;
 }
 }  // namespace internal
 }  // namespace v8
 #endif  // V8_TARGET_ARCH_PPC