[gn build] Port bfd263a

Author: llvmgnsyncbot

llvm/utils/gn/secondary/lldb/source/Expression/BUILD.gn

@@ -25,6 +25,7 @@ static_library("Expression") {
     "DWARFExpressionList.cpp",
     "DiagnosticManager.cpp",
     "Expression.cpp",
+    "ExpressionParser.cpp",
     "ExpressionTypeSystemHelper.cpp",
     "ExpressionVariable.cpp",
     "FunctionCaller.cpp",