ARM: Load undefined receiver sentinel without constant pool

Each call to emit_32 uses 5 constant pool slots:
* the "emit_32" string
* undefined (the receiver)
* the argument (heap number)
* the load IC
* the call IC

This change cuts that down 20% to 4, by loading the undefined from the heap roots.

R=verwaest@chromium.org
BUG=

Review URL: https://codereview.chromium.org/980563002

Cr-Commit-Position: refs/heads/master@{#26979}

src/arm/builtins-arm.cc

@@ -929,7 +929,9 @@ static void CallCompileOptimized(MacroAssembler* masm, bool concurrent) {
   // Push function as parameter to the runtime call.
   __ Push(r1);
   // Whether to compile in a background thread.
-  __ Push(masm->isolate()->factory()->ToBoolean(concurrent));
+  __ LoadRoot(
+      ip, concurrent ? Heap::kTrueValueRootIndex : Heap::kFalseValueRootIndex);
+  __ push(ip);
 
   __ CallRuntime(Runtime::kCompileOptimized, 2);
   // Restore receiver.

src/arm/full-codegen-arm.cc

@@ -2913,7 +2913,8 @@ void FullCodeGenerator::EmitCallWithLoadIC(Call* expr) {
     }
     // Push undefined as receiver. This is patched in the method prologue if it
     // is a sloppy mode method.
-    __ Push(isolate()->factory()->undefined_value());
+    __ LoadRoot(ip, Heap::kUndefinedValueRootIndex);
+    __ push(ip);
   } else {
     // Load the function from the receiver.
     DCHECK(callee->IsProperty());

src/arm64/full-codegen-arm64.cc

@@ -2603,7 +2603,12 @@ void FullCodeGenerator::EmitCallWithLoadIC(Call* expr) {
     }
     // Push undefined as receiver. This is patched in the method prologue if it
     // is a sloppy mode method.
-    __ Push(isolate()->factory()->undefined_value());
+    {
+      UseScratchRegisterScope temps(masm_);
+      Register temp = temps.AcquireX();
+      __ LoadRoot(temp, Heap::kUndefinedValueRootIndex);
+      __ Push(temp);
+    }
   } else {
     // Load the function from the receiver.
     DCHECK(callee->IsProperty());