Revert of [regexp] Remove remainder of native RegExpExecStub

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

Index: src/regexp/arm/regexp-macro-assembler-arm.cc
diff --git a/src/regexp/arm/regexp-macro-assembler-arm.cc b/src/regexp/arm/regexp-macro-assembler-arm.cc
index 5caaee3bc8b68cae0107a487638c570d94b4ed51..579423ff32e4351d137a7bf17e89fcd7f68cf437 100644
--- a/src/regexp/arm/regexp-macro-assembler-arm.cc
+++ b/src/regexp/arm/regexp-macro-assembler-arm.cc
@@ -41,13 +41,14 @@
  * Each call to a public method should retain this convention.
  *
  * The stack will have the following structure:
- *  - fp[52]  Isolate* isolate   (address of the current isolate)
- *  - fp[48]  direct_call        (if 1, direct call from JavaScript code,
+ *  - fp[56]  Isolate* isolate   (address of the current isolate)
+ *  - fp[52]  direct_call        (if 1, direct call from JavaScript code,
  *                                if 0, call through the runtime system).
- *  - fp[44]  stack_area_base    (high end of the memory area to use as
+ *  - fp[48]  stack_area_base    (high end of the memory area to use as
  *                                backtracking stack).
- *  - fp[40]  capture array size (may fit multiple sets of matches)
- *  - fp[36]  int* capture_array (int[num_saved_registers_], for output).
+ *  - fp[44]  capture array size (may fit multiple sets of matches)
+ *  - fp[40]  int* capture_array (int[num_saved_registers_], for output).
+ *  - fp[36]  secondary link/return address used by native call.
  *  --- sp when called ---
  *  - fp[32]  return address     (lr).
  *  - fp[28]  old frame pointer  (r11).
@@ -80,14 +81,17 @@
  *              int start_index,
  *              Address start,
  *              Address end,
+ *              Address secondary_return_address,  // Only used by native call.
  *              int* capture_output_array,
- *              int num_capture_registers,
  *              byte* stack_area_base,
- *              bool direct_call = false,
- *              Isolate* isolate);
+ *              bool direct_call = false)
  * The call is performed by NativeRegExpMacroAssembler::Execute()
  * (in regexp-macro-assembler.cc) via the CALL_GENERATED_REGEXP_CODE macro
  * in arm/simulator-arm.h.
+ * When calling as a non-direct call (i.e., from C++ code), the return address
+ * area is overwritten with the LR register by the RegExp code. When doing a
+ * direct call from generated code, the return address is placed there by
+ * the calling code, as in a normal exit frame.
  */
 
 #define __ ACCESS_MASM(masm_)