Remove .previous directives from ARM64 StackPointer assembly

The .previous directive is not supported by LLVM ARM64 assembler on Windows.
Remove all instances to fix compilation of StackPointer.cpp on ARM64 Windows.

Fixes: <inline asm>(7,1): error: unknown directive .previous

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <[email protected]>

Author: WebKit ARM64 Builder

Source/WTF/wtf/StackPointer.cpp

@@ -50,7 +50,6 @@ asm (
     "movl %esp, %eax" "\n"
     "addl $4, %eax" "\n"
     "ret" "\n"
-    ".previous" "\n"
 );
 
 #elif CPU(X86_64) && OS(WINDOWS)
@@ -80,7 +79,6 @@ asm (
     "movq  %rsp, %rax" "\n"
     "addq $8, %rax" "\n" // Account for return address.
     "ret" "\n"
-    ".previous" "\n"
 );
 
 #elif CPU(ARM64E)
@@ -93,7 +91,6 @@ asm (
     "pacibsp" "\n"
     "mov x0, sp" "\n"
     "retab" "\n"
-    ".previous" "\n"
 );
 
 #elif CPU(ARM64)
@@ -105,7 +102,6 @@ asm (
 
     "mov x0, sp" "\n"
     "ret" "\n"
-    ".previous" "\n"
 );
 
 #elif CPU(ARM_THUMB2)
@@ -119,7 +115,6 @@ asm (
 
     "mov r0, sp" "\n"
     "bx  lr" "\n"
-    ".previous" "\n"
 );
 
 #elif CPU(MIPS)
@@ -135,7 +130,6 @@ asm (
     "jr   $ra" "\n"
     "nop" "\n"
     ".set pop" "\n"
-    ".previous" "\n"
 );
 
 #elif CPU(RISCV64)
@@ -146,8 +140,7 @@ asm (
 
      "mv x10, sp" "\n"
      "ret" "\n"
-     ".previous" "\n"
-);
+ );
 
 #elif CPU(LOONGARCH64)
 asm (
@@ -157,8 +150,7 @@ asm (
 
      "move $r4, $r3" "\n"
      "jr   $r1" "\n"
-     ".previous" "\n"
-);
+ );
 
 #else
 #error "Unsupported platform: need implementation of currentStackPointer."