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

src/full-codegen/mips/full-codegen-mips.cc

Index: src/full-codegen/mips/full-codegen-mips.cc
diff --git a/src/full-codegen/mips/full-codegen-mips.cc b/src/full-codegen/mips/full-codegen-mips.cc
index 3571292e9e5856e1cedc49bd5a5b1315471c5f68..e1daa208fb79c1c438f0395f2ea2ad10376783ce 100644
--- a/src/full-codegen/mips/full-codegen-mips.cc
+++ b/src/full-codegen/mips/full-codegen-mips.cc
@@ -798,6 +798,9 @@ void FullCodeGenerator::VisitVariableDeclaration(
       PrepareForBailoutForId(proxy->id(), BailoutState::NO_REGISTERS);
       break;
     }
+
+    case VariableLocation::MODULE:
+      UNREACHABLE();
   }
 }
 
@@ -857,6 +860,9 @@ void FullCodeGenerator::VisitFunctionDeclaration(
       PrepareForBailoutForId(proxy->id(), BailoutState::NO_REGISTERS);
       break;
     }
+
+    case VariableLocation::MODULE:
+      UNREACHABLE();
   }
 }
 
@@ -1346,7 +1352,11 @@ void FullCodeGenerator::EmitVariableLoad(VariableProxy* proxy,
       __ CallRuntime(function_id);
       __ bind(&done);
       context()->Plug(v0);
+      break;
     }
+
+    case VariableLocation::MODULE:
+      UNREACHABLE();
   }
 }