Only pass isolate parameter to C helper functions that need it.

src/arm/full-codegen-arm.cc

Index: src/arm/full-codegen-arm.cc
diff --git a/src/arm/full-codegen-arm.cc b/src/arm/full-codegen-arm.cc
index 088ba583eaef6d03fbce771e8f4630faf11ddbbb..065ccb5408aa85967fdae39e116000044878c5a9 100644
--- a/src/arm/full-codegen-arm.cc
+++ b/src/arm/full-codegen-arm.cc
@@ -2803,8 +2803,9 @@ void FullCodeGenerator::EmitRandomHeapNumber(ZoneList<Expression*>* args) {
   // by computing:
   // ( 1.(20 0s)(32 random bits) x 2^20 ) - (1.0 x 2^20)).
   if (isolate()->cpu_features()->IsSupported(VFP3)) {
-    __ PrepareCallCFunction(0, r1);
-    __ CallCFunction(ExternalReference::random_uint32_function(isolate()), 0);
+    __ PrepareCallCFunction(1, r0);
+    __ mov(r0, Operand(ExternalReference::isolate_address()));
+    __ CallCFunction(ExternalReference::random_uint32_function(isolate()), 1);
 
     CpuFeatures::Scope scope(VFP3);
     // 0x41300000 is the top half of 1.0 x 2^20 as a double.
@@ -2822,10 +2823,11 @@ void FullCodeGenerator::EmitRandomHeapNumber(ZoneList<Expression*>* args) {
     __ vstr(d7, r0, HeapNumber::kValueOffset);
     __ mov(r0, r4);
   } else {
+    __ PrepareCallCFunction(2, r0);
     __ mov(r0, Operand(r4));
-    __ PrepareCallCFunction(1, r1);
+    __ mov(r1, Operand(ExternalReference::isolate_address()));
     __ CallCFunction(
-        ExternalReference::fill_heap_number_with_random_function(isolate()), 1);
+        ExternalReference::fill_heap_number_with_random_function(isolate()), 2);
   }
 
   context()->Plug(r0);