[regexp] remove some dead code.

credits to gcov.

Review URL: https://codereview.chromium.org/1528843002

Cr-Commit-Position: refs/heads/master@{#32868}

src/regexp/regexp-macro-assembler-tracer.cc

@@ -369,6 +369,14 @@ void RegExpMacroAssemblerTracer::CheckNotBackReferenceIgnoreCase(
 }
 
 
+void RegExpMacroAssemblerTracer::CheckPosition(int cp_offset,
+                                               Label* on_outside_input) {
+  PrintF(" CheckPosition(cp_offset=%d, label[%08x]);\n", cp_offset,
+         LabelToInt(on_outside_input));
+  assembler_->CheckPosition(cp_offset, on_outside_input);
+}
+
+
 bool RegExpMacroAssemblerTracer::CheckSpecialCharacterClass(
     uc16 type,
     Label* on_no_match) {

src/regexp/regexp-macro-assembler-tracer.h

@@ -51,6 +51,7 @@ class RegExpMacroAssemblerTracer: public RegExpMacroAssembler {
                                         uc16 to,
                                         Label* on_not_in_range);
   virtual void CheckBitInTable(Handle<ByteArray> table, Label* on_bit_set);
+  virtual void CheckPosition(int cp_offset, Label* on_outside_input);
   virtual bool CheckSpecialCharacterClass(uc16 type,
                                           Label* on_no_match);
   virtual void Fail();

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;