Revert "Introduce FX_Number class as a replacement for FX_atonum()."

This reverts commit a5d7ad3aa8feb08a14b5cca173d673054c1ade23.

Reason for revert: Speculative revert to get back before flake.

Original change's description:
> Introduce FX_Number class as a replacement for FX_atonum().
> 
> The issue with FX_atonum() is that it doesn't return any information
> about whether it range-checked its integer values as a signed or
> unsigned type, even though it knows this as part of its processing.
> 
> Rather than adding another out parameter to that function, create
> a class to hold all this information together.
> 
> This is the first place things went astray while diagnosing
> bug 882959, in that a large positive value was cast to float as a
> negative value. Unfortunately, this doesn't affect the related bug,
> but is a step in the right direction.
> 
> Change-Id: I0977ec8fccf85e2632a962507bdd30a1cbe6d33c
> Reviewed-on: https://pdfium-review.googlesource.com/42353
> Reviewed-by: Lei Zhang <thestig@chromium.org>
> Commit-Queue: Tom Sepez <tsepez@chromium.org>

TBR=thestig@chromium.org,tsepez@chromium.org

Change-Id: Ia56270c3daa80408fc2b23eb4384a77f03f45b82
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://pdfium-review.googlesource.com/42392
Reviewed-by: Tom Sepez <tsepez@chromium.org>
Commit-Queue: Tom Sepez <tsepez@chromium.org>

2 files changed, 19 insertions, 16 deletions

diff --git a/core/fpdfapi/parser/cpdf_number.cpp b/core/fpdfapi/parser/cpdf_number.cpp
index 23c2609e25..b75ce0766a 100644
--- a/core/fpdfapi/parser/cpdf_number.cpp
+++ b/core/fpdfapi/parser/cpdf_number.cpp
@@ -8,13 +8,14 @@
 #include "core/fxcrt/fx_stream.h"
 #include "third_party/base/ptr_util.h"
 
-CPDF_Number::CPDF_Number() {}
+CPDF_Number::CPDF_Number() : m_bInteger(true), m_Integer(0) {}
 
-CPDF_Number::CPDF_Number(int value) : m_Number(value) {}
+CPDF_Number::CPDF_Number(int value) : m_bInteger(true), m_Integer(value) {}
 
-CPDF_Number::CPDF_Number(float value) : m_Number(value) {}
+CPDF_Number::CPDF_Number(float value) : m_bInteger(false), m_Float(value) {}
 
-CPDF_Number::CPDF_Number(const ByteStringView& str) : m_Number(str) {}
+CPDF_Number::CPDF_Number(const ByteStringView& str)
+    : m_bInteger(FX_atonum(str, &m_Integer)) {}
 
 CPDF_Number::~CPDF_Number() {}
 
@@ -23,17 +24,16 @@ CPDF_Object::Type CPDF_Number::GetType() const {
 }
 
 std::unique_ptr<CPDF_Object> CPDF_Number::Clone() const {
-  return m_Number.IsInteger()
-             ? pdfium::MakeUnique<CPDF_Number>(m_Number.GetSigned())
-             : pdfium::MakeUnique<CPDF_Number>(m_Number.GetFloat());
+  return m_bInteger ? pdfium::MakeUnique<CPDF_Number>(m_Integer)
+                    : pdfium::MakeUnique<CPDF_Number>(m_Float);
 }
 
 float CPDF_Number::GetNumber() const {
-  return m_Number.GetFloat();
+  return m_bInteger ? static_cast<float>(m_Integer) : m_Float;
 }
 
 int CPDF_Number::GetInteger() const {
-  return m_Number.GetSigned();
+  return m_bInteger ? m_Integer : static_cast<int>(m_Float);
 }
 
 bool CPDF_Number::IsNumber() const {
@@ -49,12 +49,12 @@ const CPDF_Number* CPDF_Number::AsNumber() const {
 }
 
 void CPDF_Number::SetString(const ByteString& str) {
-  m_Number = FX_Number(str.AsStringView());
+  m_bInteger = FX_atonum(str.AsStringView(), &m_Integer);
 }
 
 ByteString CPDF_Number::GetString() const {
-  return m_Number.IsInteger() ? ByteString::FormatInteger(m_Number.GetSigned())
-                              : ByteString::FormatFloat(m_Number.GetFloat());
+  return m_bInteger ? ByteString::FormatInteger(m_Integer)
+                    : ByteString::FormatFloat(m_Float);
 }
 
 bool CPDF_Number::WriteTo(IFX_ArchiveStream* archive,
diff --git a/core/fpdfapi/parser/cpdf_number.h b/core/fpdfapi/parser/cpdf_number.h
index 724ae9f1f1..b5faf82bb2 100644
--- a/core/fpdfapi/parser/cpdf_number.h
+++ b/core/fpdfapi/parser/cpdf_number.h
@@ -10,7 +10,6 @@
 #include <memory>
 
 #include "core/fpdfapi/parser/cpdf_object.h"
-#include "core/fxcrt/fx_number.h"
 #include "core/fxcrt/fx_string.h"
 #include "core/fxcrt/fx_system.h"
 
@@ -35,10 +34,14 @@ class CPDF_Number final : public CPDF_Object {
   bool WriteTo(IFX_ArchiveStream* archive,
                const CPDF_Encryptor* encryptor) const override;
 
-  bool IsInteger() const { return m_Number.IsInteger(); }
+  bool IsInteger() const { return m_bInteger; }
 
- private:
-  FX_Number m_Number;
+ protected:
+  bool m_bInteger;
+  union {
+    int m_Integer;
+    float m_Float;
+  };
 };
 
 inline CPDF_Number* ToNumber(CPDF_Object* obj) {