[wasm][turboshaft] Fix Phi handling in Load Elimination some more

Multiple Phis can depend on each other, so we have to clear all their
replacements up front.

Fixed: 509268941
Change-Id: I7899b28e89ed7b470bd869fb52f7443589305171
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/7822799
Reviewed-by: Darius Mercadier <[email protected]>
Auto-Submit: Jakob Kummerow <[email protected]>
Commit-Queue: Jakob Kummerow <[email protected]>
Cr-Commit-Position: refs/heads/main@{#107278}

commit e38030f4228c8d1405fe105fc5feaa5173559e25 (HEAD -> 14.8.178.21, tag: 14.8.178.21-pgo, tag: 14.8.178.21)
Author: V8 Autoroll <v8-ci-autoroll-builder@chops-service-accounts.iam.gserviceaccount.com>
Date:   Wed May 6 13:34:13 2026 -0700

    Version 14.8.178.21
    
    Version incremented at https://cr-buildbucket.appspot.com/build/8682521216270456209
    
    Change-Id: I16a5eb6f12bf2c64d5a7eac752a09128e4eac6fb
    Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/7822581
    Bot-Commit: v8-ci-autoroll-builder@chops-service-accounts.iam.gserviceaccount.com <v8-ci-autoroll-builder@chops-service-accounts.iam.gserviceaccount.com>
    Cr-Commit-Position: refs/branch-heads/14.8@{#43}
    Cr-Branched-From: f9659283a5f8d42b3c09228cf5df606fcaf47a3d-refs/heads/14.8.178@{#1}
    Cr-Branched-From: 141232520dc4910401240c531db3af36910a0fd1-refs/heads/main@{#106240}

# Set build arguments here. See `gn help buildargs`.
is_debug = false
dcheck_always_on = false
v8_symbol_level = 2
v8_enable_object_print = true
v8_enable_sandbox = true
target_os = "linux"
target_cpu = "x64"

d8 --allow-natives-syntax exp.js

=========================Address=========================
fake object address: 1060f5d
=======================DebugPrint========================
DebugPrint: 0x16201060f5d: [JSArray]
 - map: 0x01620100d0d9 <Map[16](https://github.com/jaf0rk/cve-2026-9973-exploit/blob/HEAD/PACKED_DOUBLE_ELEMENTS)> [FastProperties]
 - prototype: 0x01620100ca3d <JSArray[0]>
 - elements: 0x016201060f5d <JSArray[2]> [PACKED_DOUBLE_ELEMENTS]
 - length: 2
 - properties: 0x0162000007e5 <FixedArray[0]>
 - All own properties (excluding elements): {
    0x16200000e19: [String] in ReadOnlySpace: #length: 0x0162001a6add <AccessorInfo name= 0x016200000e19 <String[6]: #length>, data= 0x016200000011 <undefined>> (const accessor descriptor, attrs: [W__])
 }
 // This is object address
 - elements: 0x016201060f5d <JSArray[2]> {   Unexpected elements backing store

 }
0x1620100d0d9: [Map] in OldSpace
 - map: 0x016201004939 <MetaMap (0x016201004989 <NativeContext[307]>)>
 - type: JS_ARRAY_TYPE
 - instance size: 16
 - inobject properties: 0
 - unused property fields: 0
 - elements kind: PACKED_DOUBLE_ELEMENTS
 - enum length: invalid
 - back pointer: 0x01620100d095 <Map[16](https://github.com/jaf0rk/cve-2026-9973-exploit/blob/HEAD/HOLEY_SMI_ELEMENTS)>
 - prototype_validity_cell: 0x016200000af1 <Cell value= [cleared]>
 - instance descriptors #1: 0x01620100d059 <DescriptorArray[1]>
 - transitions #1: 0x01620100d101 <TransitionArray[5]>
   Transitions #1:
     0x016200000eb5 <Symbol: (elements_transition_symbol)>: (transition to HOLEY_DOUBLE_ELEMENTS) -> 0x01620100d11d <Map[16](https://github.com/jaf0rk/cve-2026-9973-exploit/blob/HEAD/HOLEY_DOUBLE_ELEMENTS)>
 - prototype: 0x01620100ca3d <JSArray[0]>
 - constructor: 0x01620100c965 <JSFunction Array (sfi = 0x162001ac43d)>
 - dependent code: 0x0162000007f5 <Other heap object (WEAK_ARRAY_LIST_TYPE)>
 - construction counter: 0