A64: Add support for --stress_pointer_maps and --stress_environments.

src/a64/lithium-a64.cc

Index: src/a64/lithium-a64.cc
diff --git a/src/a64/lithium-a64.cc b/src/a64/lithium-a64.cc
index b14b4d7d6585cd925ddf0824d26b460cd5ddde95..5048275526f6031166819e452fbca4dc621951e0 100644
--- a/src/a64/lithium-a64.cc
+++ b/src/a64/lithium-a64.cc
@@ -717,8 +717,12 @@ void LChunkBuilder::VisitInstruction(HInstruction* current) {
     }
 #endif
 
-    // TODO(all): Add support for FLAG_stress_pointer_maps and
-    // FLAG_stress_environments.
+    if (FLAG_stress_pointer_maps && !instr->HasPointerMap()) {
+      instr = AssignPointerMap(instr);
+    }
+    if (FLAG_stress_environments && !instr->HasEnvironment()) {
+      instr = AssignEnvironment(instr);
+    }
     instr->set_hydrogen_value(current);
     chunk_->AddInstruction(instr, current_block_);
   }