[diagnostics] Fix -Wshadow

Bug: v8:12244,v8:12245
Change-Id: Ieb3129ec1e66024b5431a1deb231529b94c740f2
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3273894Reviewed-by: Andreas Haas <ahaas@chromium.org>
Commit-Queue: Zhi An Ng <zhin@chromium.org>
Cr-Commit-Position: refs/heads/main@{#77853}

src/diagnostics/basic-block-profiler.cc

@@ -174,8 +174,8 @@ std::vector<bool> BasicBlockProfiler::GetCoverageBitmap(Isolate* isolate) {
   for (int i = 0; i < list_length; ++i) {
     BasicBlockProfilerData data(
         OnHeapBasicBlockProfilerData::cast(list.Get(i)));
-    for (size_t i = 0; i < data.n_blocks(); ++i) {
-      out.push_back(data.counts_[i] > 0);
+    for (size_t j = 0; j < data.n_blocks(); ++j) {
+      out.push_back(data.counts_[j] > 0);
     }
   }
   return out;

src/diagnostics/x64/disasm-x64.cc

@@ -1956,7 +1956,6 @@ int DisassemblerX64::TwoByteOpcodeInstruction(byte* data) {
     } else if (opcode == 0xD7) {
       current += PrintOperands("pmovmskb", OPER_XMMREG_OP_ORDER, current);
     } else {
-      const char* mnemonic;
 #define SSE2_CASE(instruction, notUsed1, notUsed2, opcode) \
   case 0x##opcode:                                         \
     mnemonic = "" #instruction;                            \