[modules] Introduce new VariableLocation for module imports/exports.

src/full-codegen/ia32/full-codegen-ia32.cc

Index: src/full-codegen/ia32/full-codegen-ia32.cc
diff --git a/src/full-codegen/ia32/full-codegen-ia32.cc b/src/full-codegen/ia32/full-codegen-ia32.cc
index 66517c6702c936da8269a344afa418e3ff040c8b..85b01bdd1a6fa98baf0c03a178a330976dc568ab 100644
--- a/src/full-codegen/ia32/full-codegen-ia32.cc
+++ b/src/full-codegen/ia32/full-codegen-ia32.cc
@@ -754,6 +754,9 @@ void FullCodeGenerator::VisitVariableDeclaration(
       PrepareForBailoutForId(proxy->id(), BailoutState::NO_REGISTERS);
       break;
     }
+
+    case VariableLocation::MODULE:
+      UNREACHABLE();
   }
 }
 
@@ -809,6 +812,9 @@ void FullCodeGenerator::VisitFunctionDeclaration(
       PrepareForBailoutForId(proxy->id(), BailoutState::NO_REGISTERS);
       break;
     }
+
+    case VariableLocation::MODULE:
+      UNREACHABLE();
   }
 }
 
@@ -1281,6 +1287,9 @@ void FullCodeGenerator::EmitVariableLoad(VariableProxy* proxy,
       context()->Plug(eax);
       break;
     }
+
+    case VariableLocation::MODULE:
+      UNREACHABLE();
   }
 }