Modernize CXFA_FMSimpleExpression derived classes

Many classes still use empty bodies instead of the default-expression.

Change-Id: If77eb0836977edc8a0669cf39ec6432ba4710cca
Reviewed-on: https://pdfium-review.googlesource.com/c/pdfium/+/67130
Reviewed-by: Lei Zhang <thestig@chromium.org>
Commit-Queue: Daniel Hosseinian <dhoss@chromium.org>

xfa/fxfa/fm2js/cxfa_fmsimpleexpression.cpp

diff --git a/xfa/fxfa/fm2js/cxfa_fmsimpleexpression.cpp b/xfa/fxfa/fm2js/cxfa_fmsimpleexpression.cpp
index e29e5dc..2b254ca 100644
--- a/xfa/fxfa/fm2js/cxfa_fmsimpleexpression.cpp
+++ b/xfa/fxfa/fm2js/cxfa_fmsimpleexpression.cpp
@@ -456,7 +456,7 @@
       m_bIsSomMethod(bIsSomMethod),
       m_Arguments(std::move(pArguments)) {}
 
-CXFA_FMCallExpression::~CXFA_FMCallExpression() {}
+CXFA_FMCallExpression::~CXFA_FMCallExpression() = default;
 
 bool CXFA_FMCallExpression::IsBuiltInFunc(CFX_WideTextBuf* funcName) {
   if (funcName->GetLength() > g_BuiltInFuncsMaxLen)

xfa/fxfa/fm2js/cxfa_fmsimpleexpression.h

diff --git a/xfa/fxfa/fm2js/cxfa_fmsimpleexpression.h b/xfa/fxfa/fm2js/cxfa_fmsimpleexpression.h
index a970029..6657b56 100644
--- a/xfa/fxfa/fm2js/cxfa_fmsimpleexpression.h
+++ b/xfa/fxfa/fm2js/cxfa_fmsimpleexpression.h
@@ -65,7 +65,7 @@
 class CXFA_FMNullExpression final : public CXFA_FMSimpleExpression {
  public:
   CXFA_FMNullExpression();
-  ~CXFA_FMNullExpression() override {}
+  ~CXFA_FMNullExpression() override = default;
 
   bool ToJavaScript(CFX_WideTextBuf* js, ReturnType type) override;
 };
@@ -134,7 +134,7 @@
   CXFA_FMLogicalOrExpression(XFA_FM_TOKEN op,
                              std::unique_ptr<CXFA_FMSimpleExpression> pExp1,
                              std::unique_ptr<CXFA_FMSimpleExpression> pExp2);
-  ~CXFA_FMLogicalOrExpression() override {}
+  ~CXFA_FMLogicalOrExpression() override = default;
 };
 
 class CXFA_FMLogicalAndExpression final : public CXFA_FMBinExpression {
@@ -142,7 +142,7 @@
   CXFA_FMLogicalAndExpression(XFA_FM_TOKEN op,
                               std::unique_ptr<CXFA_FMSimpleExpression> pExp1,
                               std::unique_ptr<CXFA_FMSimpleExpression> pExp2);
-  ~CXFA_FMLogicalAndExpression() override {}
+  ~CXFA_FMLogicalAndExpression() override = default;
 };
 
 class CXFA_FMEqualExpression final : public CXFA_FMBinExpression {
@@ -150,7 +150,7 @@
   CXFA_FMEqualExpression(XFA_FM_TOKEN op,
                          std::unique_ptr<CXFA_FMSimpleExpression> pExp1,
                          std::unique_ptr<CXFA_FMSimpleExpression> pExp2);
-  ~CXFA_FMEqualExpression() override {}
+  ~CXFA_FMEqualExpression() override = default;
 };
 
 class CXFA_FMNotEqualExpression final : public CXFA_FMBinExpression {
@@ -158,7 +158,7 @@
   CXFA_FMNotEqualExpression(XFA_FM_TOKEN op,
                             std::unique_ptr<CXFA_FMSimpleExpression> pExp1,
                             std::unique_ptr<CXFA_FMSimpleExpression> pExp2);
-  ~CXFA_FMNotEqualExpression() override {}
+  ~CXFA_FMNotEqualExpression() override = default;
 };
 
 class CXFA_FMGtExpression final : public CXFA_FMBinExpression {
@@ -166,7 +166,7 @@
   CXFA_FMGtExpression(XFA_FM_TOKEN op,
                       std::unique_ptr<CXFA_FMSimpleExpression> pExp1,
                       std::unique_ptr<CXFA_FMSimpleExpression> pExp2);
-  ~CXFA_FMGtExpression() override {}
+  ~CXFA_FMGtExpression() override = default;
 };
 
 class CXFA_FMGeExpression final : public CXFA_FMBinExpression {
@@ -174,7 +174,7 @@
   CXFA_FMGeExpression(XFA_FM_TOKEN op,
                       std::unique_ptr<CXFA_FMSimpleExpression> pExp1,
                       std::unique_ptr<CXFA_FMSimpleExpression> pExp2);
-  ~CXFA_FMGeExpression() override {}
+  ~CXFA_FMGeExpression() override = default;
 };
 
 class CXFA_FMLtExpression final : public CXFA_FMBinExpression {
@@ -182,7 +182,7 @@
   CXFA_FMLtExpression(XFA_FM_TOKEN op,
                       std::unique_ptr<CXFA_FMSimpleExpression> pExp1,
                       std::unique_ptr<CXFA_FMSimpleExpression> pExp2);
-  ~CXFA_FMLtExpression() override {}
+  ~CXFA_FMLtExpression() override = default;
 };
 
 class CXFA_FMLeExpression final : public CXFA_FMBinExpression {
@@ -190,7 +190,7 @@
   CXFA_FMLeExpression(XFA_FM_TOKEN op,
                       std::unique_ptr<CXFA_FMSimpleExpression> pExp1,
                       std::unique_ptr<CXFA_FMSimpleExpression> pExp2);
-  ~CXFA_FMLeExpression() override {}
+  ~CXFA_FMLeExpression() override = default;
 };
 
 class CXFA_FMPlusExpression final : public CXFA_FMBinExpression {
@@ -198,7 +198,7 @@
   CXFA_FMPlusExpression(XFA_FM_TOKEN op,
                         std::unique_ptr<CXFA_FMSimpleExpression> pExp1,
                         std::unique_ptr<CXFA_FMSimpleExpression> pExp2);
-  ~CXFA_FMPlusExpression() override {}
+  ~CXFA_FMPlusExpression() override = default;
 };
 
 class CXFA_FMMinusExpression final : public CXFA_FMBinExpression {
@@ -206,7 +206,7 @@
   CXFA_FMMinusExpression(XFA_FM_TOKEN op,
                          std::unique_ptr<CXFA_FMSimpleExpression> pExp1,
                          std::unique_ptr<CXFA_FMSimpleExpression> pExp2);
-  ~CXFA_FMMinusExpression() override {}
+  ~CXFA_FMMinusExpression() override = default;
 };
 
 class CXFA_FMMulExpression final : public CXFA_FMBinExpression {
@@ -214,7 +214,7 @@
   CXFA_FMMulExpression(XFA_FM_TOKEN op,
                        std::unique_ptr<CXFA_FMSimpleExpression> pExp1,
                        std::unique_ptr<CXFA_FMSimpleExpression> pExp2);
-  ~CXFA_FMMulExpression() override {}
+  ~CXFA_FMMulExpression() override = default;
 };
 
 class CXFA_FMDivExpression final : public CXFA_FMBinExpression {
@@ -222,7 +222,7 @@
   CXFA_FMDivExpression(XFA_FM_TOKEN op,
                        std::unique_ptr<CXFA_FMSimpleExpression> pExp1,
                        std::unique_ptr<CXFA_FMSimpleExpression> pExp2);
-  ~CXFA_FMDivExpression() override {}
+  ~CXFA_FMDivExpression() override = default;
 };
 
 class CXFA_FMUnaryExpression : public CXFA_FMSimpleExpression {
@@ -244,19 +244,19 @@
 class CXFA_FMPosExpression final : public CXFA_FMUnaryExpression {
  public:
   explicit CXFA_FMPosExpression(std::unique_ptr<CXFA_FMSimpleExpression> pExp);
-  ~CXFA_FMPosExpression() override {}
+  ~CXFA_FMPosExpression() override = default;
 };
 
 class CXFA_FMNegExpression final : public CXFA_FMUnaryExpression {
  public:
   explicit CXFA_FMNegExpression(std::unique_ptr<CXFA_FMSimpleExpression> pExp);
-  ~CXFA_FMNegExpression() override {}
+  ~CXFA_FMNegExpression() override = default;
 };
 
 class CXFA_FMNotExpression final : public CXFA_FMUnaryExpression {
  public:
   explicit CXFA_FMNotExpression(std::unique_ptr<CXFA_FMSimpleExpression> pExp);
-  ~CXFA_FMNotExpression() override {}
+  ~CXFA_FMNotExpression() override = default;
 };
 
 class CXFA_FMCallExpression final : public CXFA_FMSimpleExpression {