[regexp] remove some dead code.

src/regexp/regexp-macro-assembler.h

Index: src/regexp/regexp-macro-assembler.h
diff --git a/src/regexp/regexp-macro-assembler.h b/src/regexp/regexp-macro-assembler.h
index 73cc52a8358c7ba52da8eb6a77e326b50a5c2d29..e8f7360efa24fa31c0c2ffacd2c4296888500c58 100644
--- a/src/regexp/regexp-macro-assembler.h
+++ b/src/regexp/regexp-macro-assembler.h
@@ -104,17 +104,12 @@ class RegExpMacroAssembler {
 
   // Checks whether the given offset from the current position is before
   // the end of the string.  May overwrite the current character.
-  virtual void CheckPosition(int cp_offset, Label* on_outside_input) {
-    LoadCurrentCharacter(cp_offset, on_outside_input, true);
-  }
+  virtual void CheckPosition(int cp_offset, Label* on_outside_input) = 0;
   // Check whether a standard/default character class matches the current
   // character. Returns false if the type of special character class does
   // not have custom support.
   // May clobber the current loaded character.
-  virtual bool CheckSpecialCharacterClass(uc16 type,
-                                          Label* on_no_match) {
-    return false;
-  }
+  virtual bool CheckSpecialCharacterClass(uc16 type, Label* on_no_match) = 0;
   virtual void Fail() = 0;
   virtual Handle<HeapObject> GetCode(Handle<String> source) = 0;
   virtual void GoTo(Label* label) = 0;