PPC: Remove more dead code now that legacy const is gone

Port 757221e5

Original commit message:

    Neither globals nor lookup slots can be hole-initialized anymore, thus
    removing some dead code from the code generators and runtime-scopes.

R=adamk@chromium.org, joransiu@ca.ibm.com, jyan@ca.ibm.com, michael_dawson@ca.ibm.com, mbrandy@us.ibm.com

BUG=
LOG=N

Review-Url: https://codereview.chromium.org/2061443002
Cr-Commit-Position: refs/heads/master@{#36899}

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

@@ -765,15 +765,8 @@ void FullCodeGenerator::VisitVariableDeclaration(
       __ mov(r5, Operand(variable->name()));
       // Declaration nodes are always introduced in one of four modes.
       DCHECK(IsDeclaredVariableMode(mode));
-      // Push initial value, if any.
-      // Note: For variables we must not push an initial value (such as
-      // 'undefined') because we may have a (legal) redeclaration and we
-      // must not destroy the current value.
-      if (hole_init) {
-        __ LoadRoot(r3, Heap::kTheHoleValueRootIndex);
-      } else {
-        __ LoadSmiLiteral(r3, Smi::FromInt(0));  // Indicates no initial value.
-      }
+      DCHECK(!hole_init);
+      __ LoadSmiLiteral(r3, Smi::FromInt(0));  // Indicates no initial value.
       __ Push(r5, r3);
       __ Push(Smi::FromInt(variable->DeclarationPropertyAttributes()));
       __ CallRuntime(Runtime::kDeclareLookupSlot);