Use the iOS ABI when running SIMARM on Mac or targeting iOS.

runtime/vm/assembler_arm.cc

Index: runtime/vm/assembler_arm.cc
diff --git a/runtime/vm/assembler_arm.cc b/runtime/vm/assembler_arm.cc
index d7673d03f859ba273595efd75e389be81130fbc0..31824b1a8484a323c3a1130b7da93fba372e11c3 100644
--- a/runtime/vm/assembler_arm.cc
+++ b/runtime/vm/assembler_arm.cc
@@ -3309,7 +3309,10 @@ void Assembler::CallRuntime(const RuntimeEntry& entry,
 void Assembler::EnterDartFrame(intptr_t frame_size) {
   ASSERT(!constant_pool_allowed());
 
-  // Registers are pushed in descending order: R5 | R6 | R11 | R14.
+  // Registers are pushed in descending order: R5 | R6 | R7/R11 | R14.
+  COMPILE_ASSERT(PP < CODE_REG);
+  COMPILE_ASSERT(CODE_REG < FP);
+  COMPILE_ASSERT(FP < LR);
   EnterFrame((1 << PP) | (1 << CODE_REG) | (1 << FP) | (1 << LR), 0);
 
   // Setup pool pointer for this dart function.