X87: [Atomics] code stubs for atomic operations.

src/x87/interface-descriptors-x87.cc

Index: src/x87/interface-descriptors-x87.cc
diff --git a/src/x87/interface-descriptors-x87.cc b/src/x87/interface-descriptors-x87.cc
index 78606e7a2b79ef011e4405c0684e19b3eb395592..2be79285af189a840233d857af6d7456c51445f3 100644
--- a/src/x87/interface-descriptors-x87.cc
+++ b/src/x87/interface-descriptors-x87.cc
@@ -427,6 +427,15 @@ void ResumeGeneratorDescriptor::InitializePlatformSpecific(
   data->InitializePlatformSpecific(arraysize(registers), registers);
 }
 
+void AtomicsLoadDescriptor::InitializePlatformSpecific(
+    CallInterfaceDescriptorData* data) {
+  Register registers[] = {
+      edx,  // the typedarray object
+      eax   // the index to load (untagged)
+  };
+  data->InitializePlatformSpecific(arraysize(registers), registers);
+}
+
 }  // namespace internal
 }  // namespace v8