[Interpreter] Add support for loading literals from the constant pool.

src/interpreter/interpreter.cc

Index: src/interpreter/interpreter.cc
diff --git a/src/interpreter/interpreter.cc b/src/interpreter/interpreter.cc
index f3a6512bfbab5fc46a97556af9b9509b92982d1f..82b0b4772f6b4585ef4d2979d47334986c7b1ba2 100644
--- a/src/interpreter/interpreter.cc
+++ b/src/interpreter/interpreter.cc
@@ -106,6 +106,17 @@ void Interpreter::DoLdaSmi8(compiler::InterpreterAssembler* assembler) {
 }
 
 
+// LdaConstant <idx>
+//
+// Load constant literal at |idx| in the constant pool into the accumulator.
+void Interpreter::DoLdaConstant(compiler::InterpreterAssembler* assembler) {
+  Node* index = __ BytecodeOperandIdx(0);
+  Node* constant = __ LoadConstantPoolEntry(index);
+  __ SetAccumulator(constant);
+  __ Dispatch();
+}
+
+
 // LdaUndefined
 //
 // Load Undefined into the accumulator.