Enable Float32Array_getIndexed on X64 now that cvtss2sd is implemented

runtime/vm/intrinsifier_x64.cc

Index: runtime/vm/intrinsifier_x64.cc
diff --git a/runtime/vm/intrinsifier_x64.cc b/runtime/vm/intrinsifier_x64.cc
index fce55dadd96b3300ab147c49bac9b8c74557bf50..03f42778c6f31dcfece67b6cb2d4df65dfc949b0 100644
--- a/runtime/vm/intrinsifier_x64.cc
+++ b/runtime/vm/intrinsifier_x64.cc
@@ -518,8 +518,7 @@ bool Intrinsifier::Uint32Array_getIndexed(Assembler* assembler) {
 }
 
 bool Intrinsifier::Float32Array_getIndexed(Assembler* assembler) {
-  // Temporary fix until cvtss2sd implemented.
-  /*Label fall_through;
+  Label fall_through;
   TestByteArrayIndex(assembler, &fall_through);
   // After TestByteArrayIndex:
   // * RAX has the base address of the byte array.
@@ -541,7 +540,7 @@ bool Intrinsifier::Float32Array_getIndexed(Assembler* assembler) {
   // Store XMM7 into double instance.
   __ movsd(FieldAddress(RAX, Double::value_offset()), XMM7);
   __ ret();
-  __ Bind(&fall_through); */
+  __ Bind(&fall_through);
   return false;
 }