ARM: Support hardfloat in SCons build and make it a build time setting

src/arm/code-stubs-arm.cc

Index: src/arm/code-stubs-arm.cc
diff --git a/src/arm/code-stubs-arm.cc b/src/arm/code-stubs-arm.cc
index 721af0e186e4a9cdb8bb3967836ea29ff3ab9ba2..95fb3273d5952e93da6581d412806d5cfcca6192 100644
--- a/src/arm/code-stubs-arm.cc
+++ b/src/arm/code-stubs-arm.cc
@@ -831,8 +831,7 @@ void FloatingPointHelper::CallCCodeForDoubleOperation(
   // through pop(pc) below.
   __ push(lr);
   __ PrepareCallCFunction(0, 2, scratch);
-  if (FLAG_hardfloat) {
-    ASSERT(CpuFeatures::IsSupported(VFP3));
+  if (masm->use_eabi_hardfloat()) {
     CpuFeatures::Scope scope(VFP3);
     __ vmov(d0, r0, r1);
     __ vmov(d1, r2, r3);
@@ -842,7 +841,7 @@ void FloatingPointHelper::CallCCodeForDoubleOperation(
                    0, 2);
   // Store answer in the overwritable heap number. Double returned in
   // registers r0 and r1 or in d0.
-  if (FLAG_hardfloat) {
+  if (masm->use_eabi_hardfloat()) {
     CpuFeatures::Scope scope(VFP3);
     __ vstr(d0,
             FieldMemOperand(heap_number_result, HeapNumber::kValueOffset));
@@ -1192,8 +1191,7 @@ static void EmitTwoNonNanDoubleComparison(MacroAssembler* masm,
     // Call C routine that may not cause GC or other trouble.
     __ push(lr);
     __ PrepareCallCFunction(0, 2, r5);
-    if (FLAG_hardfloat) {
-      ASSERT(CpuFeatures::IsSupported(VFP3));
+    if (masm->use_eabi_hardfloat()) {
       CpuFeatures::Scope scope(VFP3);
       __ vmov(d0, r0, r1);
       __ vmov(d1, r2, r3);
@@ -2854,7 +2852,7 @@ void TranscendentalCacheStub::GenerateCallCFunction(MacroAssembler* masm,
 
   __ push(lr);
   __ PrepareCallCFunction(0, 1, scratch);
-  if (FLAG_hardfloat) {
+  if (masm->use_eabi_hardfloat()) {
     __ vmov(d0, d2);
   } else {
     __ vmov(r0, r1, d2);