Port some GC fixes from the bleeding edge to the 2.3 branch. These are:...

src/arm/ic-arm.cc

Index: src/arm/ic-arm.cc
===================================================================
--- src/arm/ic-arm.cc	(revision 5701)
+++ src/arm/ic-arm.cc	(working copy)
@@ -1427,9 +1427,12 @@
 
     __ bind(&box_int);
     // Allocate a HeapNumber for the result and perform int-to-double
-    // conversion. Use r0 for result as key is not needed any more.
+    // conversion.  Don't touch r0 or r1 as they are needed if allocation
+    // fails.
     __ LoadRoot(r6, Heap::kHeapNumberMapRootIndex);
-    __ AllocateHeapNumber(r0, r3, r4, r6, &slow);
+    __ AllocateHeapNumber(r5, r3, r4, r6, &slow);
+    // Now we can use r0 for the result as key is not needed any more.
+    __ mov(r0, r5);
 
     if (CpuFeatures::IsSupported(VFP3)) {
       CpuFeatures::Scope scope(VFP3);