PPC: [runtime] Initial step towards switching Execution::Call to callable.

Port d5bbd45f

Original commit message:
    Currently Execution::Call (and friends) still duplicate a lot of the
    Call sequence logic that should be encapsulated in the Call and
    CallFunction builtins. So the plan now is to switch Execution::Call
    to accept any Callable and just pass that through to the Call builtin.

R=bmeurer@chromium.org, joransiu@ca.ibm.com, jyan@ca.ibm.com, michael_dawson@ca.ibm.com, dstence@us.ibm.com
BUG=v8:4413
LOG=n

Review URL: https://codereview.chromium.org/1347213003

Cr-Commit-Position: refs/heads/master@{#30813}

src/ppc/builtins-ppc.cc

@@ -791,8 +791,7 @@ static void Generate_JSEntryTrampolineHelper(MacroAssembler* masm,
       CallConstructStub stub(masm->isolate(), NO_CALL_CONSTRUCTOR_FLAGS);
       __ CallStub(&stub);
     } else {
-      ParameterCount actual(r3);
-      __ InvokeFunction(r4, actual, CALL_FUNCTION, NullCallWrapper());
+      __ Call(masm->isolate()->builtins()->Call(), RelocInfo::CODE_TARGET);
     }
     // Exit the JS frame and remove the parameters (except function), and
     // return.