[Interpreter] Add support for global declarations and load/store of global variables

src/interpreter/bytecodes.h

Index: src/interpreter/bytecodes.h
diff --git a/src/interpreter/bytecodes.h b/src/interpreter/bytecodes.h
index cb09f6c4b2d1b302d488eda922a5c2c863fe161c..5814ff9ce9210f01f734381d238ce1d9e6cb32ac 100644
--- a/src/interpreter/bytecodes.h
+++ b/src/interpreter/bytecodes.h
@@ -43,8 +43,12 @@ namespace interpreter {
   V(LdaTrue, OperandType::kNone)                                           \
   V(LdaFalse, OperandType::kNone)                                          \
                                                                            \
-  /* Load globals */                                                       \
+  /* Globals */                                                            \
   V(LdaGlobal, OperandType::kIdx)                                          \
+  V(StaGlobal, OperandType::kIdx)                                          \
+                                                                           \
+  /* Context operations */                                                 \
+  V(LdaContextSlot, OperandType::kReg, OperandType::kIdx)                  \
                                                                            \
   /* Register-accumulator transfers */                                     \
   V(Ldar, OperandType::kReg)                                               \
@@ -153,6 +157,10 @@ class Register {
   int ToParameterIndex(int parameter_count) const;
   static int MaxParameterIndex();
 
+  // Returns the register for the function's outer context.
+  static Register function_context();
+  bool is_function_context() const;
+
   static Register FromOperand(uint8_t operand);
   uint8_t ToOperand() const;