Convert float64 to float32 when coerced with a heapf32 assignment.

src/wasm/asm-wasm-builder.cc

Index: src/wasm/asm-wasm-builder.cc
diff --git a/src/wasm/asm-wasm-builder.cc b/src/wasm/asm-wasm-builder.cc
index 9144b0449b24e5ffedb5420c73fd6364ab280bc4..91c3a8ee16ddb658e4431b47a120137c080f30a0 100644
--- a/src/wasm/asm-wasm-builder.cc
+++ b/src/wasm/asm-wasm-builder.cc
@@ -694,6 +694,12 @@ class AsmWasmBuilderImpl : public AstVisitor {
     is_set_op_ = true;
     RECURSE(Visit(expr->target()));
     DCHECK(!is_set_op_);
+    // Assignment to heapf32 from float64 converts.
+    if (TypeOf(expr->value()) == kAstF64 && expr->target()->IsProperty() &&
+        expr->target()->AsProperty()->obj()->bounds().lower->Is(
+            cache_.kFloat32Array)) {
+      current_function_builder_->Emit(kExprF32ConvertF64);
+    }
     RECURSE(Visit(expr->value()));
     if (in_init) {
       UnLoadInitFunction();